THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 

GIFT  OF 


SAN  FRANCISCO 
COUNTY  MEDICAL  SOCIETY 


A  MANUAL 

OF 

X-RAY  TECHNIC 


BY 

ARTHUR  C.  CHRISTIE 

CAPTAIN,  MEDICAL  CORPS,  U.  S.  ARMY  ;   INSTRUCTOR  IN  RADIOLOGY  AND  OPERATIVE 
SURGERY,  ARMY  MEDICAL  SCHOOL,  WASHINGTON,  D.  C. 


WITH  42  ILLUSTRATIONS 


PHILADELPHIA  &  LONDON 
J.  B.  LIPPINCOTT  COMPANY 


COPYRIGHT,   1913.   BY  J.   B.   LIPPINCOTT  COMPANY 


PRINTED    BY   J.    B.   LIPPINCOTT   COMPANY 

AT  THE  WASHINGTON  SQUARE  PRESS 

PHILADELPHIA,    U.  S.  A. 


Bionedieal 

Library 

WW 
/60 

PREFACE 

This  short  manual  on  the  technic  of  X-ray 
examination  has  been  prepared  with  a  view  to  the 
needs  of  the  medical  service  of  the  United  States 
Army.  The  small  number  of  medical  officers  in  the 
service  necessitates  frequent  change  of  station,  so  that 
it  often  becomes  necessary  for  one  to  familiarize  him- 
self in  a  comparatively  short  time  with  the  essentials 
of  radiologic  technic.  With  this  in  mind  it  has  been 
the  author's  aim  to  limit  this  work  to  the  absolute 
essentials,  a  knowledge  of  which  will  enable  the 
operator  to  do  satisfactory  work  in  X-ray  diagnosis. 

The  book  may  also  be  found  useful  by  that  in- 
creasingly large  number  of  physicians  and  surgeons 
in  private  practice  who  find  it  necessary  or  expedient 
to  do  their  own  X-ray  work  for  diagnosis.    Resort  to 
a  specialist  in  radiology  is  earnestly  reconmiended 
-^-^  whenever  such  services  can  be  obtained,  but  in  the 
^  smaller  cities  and  towns  this  is  often  impossible.    It 
I   is  believed  that  mastery  of  the  facts  contained  in  this 
^  manual  will  enable  those  so  situated  to  do  satisfactory 
^   radiography. 

^  In  the  preparation  of  this  book  many  of  the  larger 
^  text-books  and  many  monographs  have  been  freely 
^  drawn  upon.  It  has  not  been  deemed  necessary,  how- 
v^  iii 


iv  PREFACE 

ever,  to  give  an  extensive  bibliography,  for  the 
publications  in  the  entire  field  of  radiology,  from  the 
time  of  the  discovery  of  the  X-ray  up  to  the  present, 
are  covered  in  that  excellent  work,  "  Die  Rontgen- 
Literatur,"  by  Prof.  Dr.  Hermann  Gocht. 

Only  a  few  reproductions  of  radiograms  are  pub- 
lished as  illustrations  to  the  text  because  it  is  believed 
that  ability  to  interpret  radiograms  can  be  gained 
only  by  experience  with  the  originals. 

Every  X-ray  operator  is  urged  to  make  himself 
thoroughly  familiar  with  the  details  of  construction  of 
the  particular  apparatus  with  which  he  is  working. 
He  is  then  in  position  to  keep  it  constantly  at  its  point 
of  maximum  efficiency.  With  his  apparatus  in  good 
condition  he  can  then  gradually  master  the  small  de- 
tails so  essential  to  good  X-ray  work,  and  with 
practice  in  examining  radiograms  he  will  finally 
acquire  ability  to  properly  interpret  them  and  so  to 
arrive  at  correct  diagnoses. 

A.  C.  Christie. 

Washington,  D.  C,  October,  1913. 


CONTENTS 


CHAPTEB  PAGE 

I.    Electricity  and  Magnetism 1 

II.    The  X-ray.    History  and  Properties 10 

III.  Apparatus  for  the  Production  of  X-rays 13 

IV.  Apparatus  for  Exciting  the  X-ray  Tube 25 

V.    Apparatus  for  Exciting  the  X-ray  Tube  (Continued) 36 

VI.     Radiography 47 

VII.    Fluoroscopy.  Stereoscopic    Radiography.    Localization   of 

Foreign  Bodies 56 

VIII.    Diseases  and  Injuries  of  Bones  and  Joints 65 

IX.    X-ray  Examination  of  the  Head 72 

X.    The  Thorax 76 

XI.    X-RAY  Examination  of  the  Alimentary  Canal 84 

XII.    The  Urinary  System 95 

Index 101 


ILLUSTRATIONS 


Fig.  Page. 

1.  The  Galvanic  Cell 2 

2.  Cells  Gboitped  in  Series 5 

3.  Cells  Grouped  in  Parallel 5 

4.  Action  of  Bar  Magnet  on  Iron  Filings 8 

5.  Solenoid 9 

6.  Electro-magnet 9 

7.  Early  Type  of  X-eat  Tube 14 

8.  Jackson's  Focus  Tube 15 

9.  Modern  Type  of  X-ray  or  Focus  Tube 15 

10.  Queen's  Self-regulating  Tube 17 

11.  The  Oscilloscope 26 

12.  Valve  Tube 27 

13.  The  Wehnelt  Electrolytic  Interrupter 31 

14.  Aluminum  Cell  Rectifier 34 

15.  Ring  Type  of  Transformer 37 

16.  Diagram  of  Connections  of  Interrupterless  Apparatus 39 

17-18.  Illustrating  Rectification  of  Current  by  Revolving  Discs  42 

19.  Diagram  of  Connections  of  an  "Interrupterless"  Apparatus 

Operating  on  an  Alternating  Current 43 

20.  Rheostat 46 

21.  Position  for  Lateral  Radiography  of  Head 74 

22.  Radiogr-why  of  Frontal  Sinuses 74 

23.  Intra-oral  Method  of  Dental  Radiography 74 

24.  Constriction  of  Cardiac  End  of  Stomach 86 

25-28.  Types  of  Norm.\l  Stomach  and  Duodenal  Cap 88 

29.  Small  Deformed  Cap  Due  to  Adhesions  Accompanying  Chole- 

cystitis   88 

30.  Extensive  Adhesions  of  Pyloric  End  of  Stomach  Due  to  Large 

Ulcer 88 

31.  Adhesions  Causing  Distortion  of  Cap,  Result  of  Old  Ulcer...  88 

32.  Carcinoma  of  Stomach 88 

vii 


viii  ILLUSTRATIONS 

33.  Obstruction  at  Pyloric  End  of  Stomach,  Probably  Carcinoma.  90 

34.  ANGTJL.4TION   of   CaP   AND   "UnDER-SHOT"   APPEARANCE  OF  StOMACH  .    90 

35.  Enlarged  and  Prolapsed  Stomach 90 

36.  Enlarged  Stomach 90 

37.  Ptosis  of  Stomach,  Patient  Erect 92 

38.  Obstruction  in  Second  Part  of  Duodenum 92 

39.  Colon  and  Sigmoid  with  Patient  Prone 92 

40.  Same  Case  with  Patient  Erect 92 

41.  Dilated  C^cum 92 

42.  Same  Care  After  Operation  (Plication),  Showmng  much  Smaller 

CiECUM 92 


A  MANUAL  OF 

X-RAY  TECHNIC 

CHAPTER  I. 

Electricity  and  Magnetism. 

Nature  and  Properties. — The  nature  of  elec- 
tricity is  known  only  by  its  effects.  The  word  is  de- 
rived from  the  Greek  elektron,  meaning  amber,  in 
which  substance  Thales,  about  600  B.C.  first  noticed 
some  of  the  phenomena  of  electricity.  The  word  "  elec- 
trics "  was  first  applied  by  Dr.  Gilbert  about  the  year 
1600  A.D.  to  certain  substances  like  amber,  sealing 
wax,  etc.,  which  become  electrified  by  friction.  The 
phenomena  of  electricity  are  supposed  to  be  due  to 
some  stress  or  strain  in  the  ether. 

Electricity  may  be  either  static  or  dynamic. 

Static  electricity  is  electricity  at  rest;  it  is  pro- 
duced by  some  form  of  friction  or  *'  influence " 
machine. 

Dynamic  electricity  may  be  galvanic  or  faradic. 

Faradic  electricity  is  a  derived  (induced)  form  of 
electricity,  so  named  from  Michael  Faraday,  in  which 
there  are  rapid  alternations  of  direction. 

Galvanic  electricity  is  that  produced  by  the  gal- 


2  A  MANUAL  OF  X-RAY  TECHNIC 

vanic  cell,  which,  in  its  simplest  form,  consists  of  a 
jar  of  dilute  sulphuric  acid  in  which  are  dipped  a  plate 
of  zinc  and  one  of  copper  (Fig.  1). 

According  to  the  theory  of  Arrhenius  the  affinity 
of  the  zinc  for  the  acid  radical  SO4  starts  a  chemical 


Fig.  1. — The  galvanic  cell. 

reaction  which  results  in  the  determination  of  positive 
ions  toward  the  copper  and  of  negative  ions  toward 
the  zinc.  In  consequence  of  this  ionic  movement  an 
electrical  current  is  produced  from  the  zinc  to  the 
copper  through  the  liquid,  and  outside  of  the  cell 
from  the  copper  to  the  zinc  through  a  connecting 
wire. 


ELECTRICITY  AND  MAGNETISM  3 

Polarization  of  a  galvanic  cell  takes  place  by  the 
collection  of  bubbles  of  hydrogen  gas  on  the  copper 
plate  and  interferes  with  or  stops  the  action  of  the 
cell.    Various  devices  have  been  used  to  prevent  this. 

Types  of  Cells. — There  are  many  different  types 
of  cells,  but  only  two  will  be  described  here. 

The  Daniell  cell  consists  of  a  zinc  plate  immersed 
in  dilute  sulphuric  acid  contained  in  a  porous  vessel, 
outside  of  which  is  a  perforated  copper  plate  sur- 
rounded by  a  solution  of  copper  sulphate.  The 
hydrogen  is  taken  up  by  the  sulphate  before  it  reaches 
the  copper  plate.  This  cell  is  very  constant  because 
polarization  is  entirely  prevented. 

The  potassium  bichromate  cell  consists  of  zinc 
and  carbon  plates  immersed  in  a  solution  of  potassium 
bichromate  in  dilute  sulphuric  acid.  The  action  of 
the  sulphuric  acid  on  the  bichromate  liberates  chromic 
acid,  which  oxidizes  the  hydrogen  to  form  water  and 
thus  prevents  polarization. 

Definitions  of  Electrical  Terms. — The  ohm 
is  the  unit  of  electrical  resistance  and  is  represented 
by  the  resistance  of  a  column  of  mercury  106.3  cm. 
long  and  14.4521  gm.  in  mass  at  0°C. 

The  ampere  is  the  unit  of  current  strength  and  is 
that  current  which  deposits  silver  at  the  rate  of 
0.001118  gm.  per  second. 


4  A  MANUAL  OF  X-RAY  TECHNIC 

The  volt  is  the  unit  of  electrical  pressure  or 
electro-motive  force;  it  is  that  electro-motive  force 
which  applied  to  one  ohm  produces  one  ampere. 

The  coulomh  is  the  unit  of  quantity,  being  the 
quantity  of  electricity  conveyed  by  one  ampere  in  one 
second. 

The  watt  is  the  unit  of  power.  One  ampere  with 
a  pressure  of  one  volt  produces  one  watt. 

These  terms  are  analogous  to  certain  hydraulic 
terms.  The  voltage  or  electro-motive  force  corre- 
sponds to  the  head  or  pressure  of  water.  Electrical 
resistance,  the  unit  of  which  is  the  ohm,  is  analogous 
to  the  frictional  resistance  to  the  flow  of  water  in  a 
pipe.  The  current  strength,  whose  unit  is  the  ampere, 
is  represented  by  the  rate  of  flow  of  the  water  through 
the  pipe.  The  quantity  of  electricity  per  second 
(coulomb)  corresponds  to  the  amount  of  water  de- 
livered per  second.  In  other  words,  if  an  electro- 
motive force  of  one  volt  is  working  against  a  re- 
sistance of  one  ohm  it  produces  a  current  of  one 
ampere,  which,  flowing  for  one  second,  produces  a 
coulomb  of  electricity. 

Ohm's  Law. — Current  strength  in  amperes  is 
equal  to  the  electro-motive  force  in  volts  divided  by 
the  resistance  of  ohms. 

C=^OTE=CxRorR  =  ~ 


ELECTRICITY  AND  MAGNETISM  5 

Methods  of  Grouping  Galvanic  Cells. — Cells 
may  be  grouped  in  series  or  in  parallel.  They  are 
grouped  in  series  (Fig.  2)  when  the  positive  pole  of 
one  is  connected  to  the  negative  of  the  next,  and  so  on. 
The  grouping  is  in  parallel  or  multiple  arc  (Fig.  3) 

Fig.  2. — Cells  grouped  in  series. 

when  all  of  the  positive  poles  are  connected  together 
on  one  side  and  all  of  the  negatives  on  the  other. 

By  connecting  cells  in  series  a  relatively  high 
voltage  may  be  obtained.    The  E.  M.  F.  is  made  to 

Fig.  3. — Cells  grouped  in  parallel. 

equal  the  E.  M.  F.  of  each  cell  multiplied  by  the 
number  of  cells.  With  n  cells  grouped  in  this  manner 
we  have  the  following  adaptation  of   Ohm's  law: 

nr-{-R' 

R  being  the  external  and  r  the  internal  resistance. 
From  this  it  is  evident  that  when  the  external  resis- 


6  A  MANUAL  OF  X-RAY  TECHNIC 

tance  is  great,  grouping  cells  in  series  will  give  a 
greater  current  than  parallel  grouping. 

By  connecting  cells  in  parallel  the  E.  M.  F.  re- 
mains that  of  only  one  cell,  while  the  resistance  be- 
comes that  of  one  cell  divided  by  the  number  of  cells. 
The  amperage  is  thus  increased  and  becomes  the 
amperage  of  one  cell  multiplied  by  the  number  of 
cells.     The   formula  for   Ohm's  law  now  becomes 


n 


This  method  of  grouping  would  therefore  give  the 
best  results  when  the  external  resistance  is  small. 

Kinds  of  Electrification. — Electrification  may 
be  manifested  by  repulsion  as  well  as  by  attraction, 
and  is  of  two  kinds,  opposite  in  character.  The  elec- 
trification developed  by  rubbing  glass  with  silk  is 
called  positive,  and  that  developed  by  rubbing  sealing 
wax  with  flannel  is  called  negative.  Bodies  similarly 
electrified  repel  each  other  and  those  oppositely  elec- 
trified attract  each  other. 

Conduction. — Electrification  by  conduction  is 
the  process  of  charging  a  body  by  putting  it  in  contact 
with  an  electrified  body.  The  charge  thus  produced 
is  of  the  same  kind  as  that  of  the  communicating  body. 

Induction. — This  is  the  process  of  electrifying  a 
body  by  bringing  it  near  to,  but  not  in  contact  with,  an 
electrified  body.    The  charge  thus  produced  is  of  the 


ELECTRICITY  AND  MAGNETISM  7 

opposite  kind  to  that  of  the  communicating  body.  A 
current  of  electricity  in  one  of  two  wires  placed  near 
each  other  produces  no  effect  in  the  second  wire  so 
long  as  the  current  flows  steadily,  but  whenever  the 
current  is  increased  or  decreased  in  strength  a  current 
is  "  induced  "  in  the  second  wire.  This  current  in  the 
second  wire  depends  upon  the  presence  of  a  "  field  of 
force "  which  surrounds  every  electrically  charged 
body.  At  the  instant  when  the  primary  current  be- 
gins or  increases  in  strength  a  weak  current  in  the 
opposite  direction  is  generated  in  the  secondary  wire ; 
at  the  instant  when  the  primary  current  stops  or  de- 
creases in  strength  a  strong  current  in  the  same  direc- 
tion is  generated  in  the  secondary. 

Magnetism. — Magnetism  is  the  property  by 
virtue  of  which  a  body  attracts  iron  or  steel,  and  which 
causes  the  iron  or  steel  when  suspended  to  take  a 
position  pointing  approximately  north  and  south. 

A  magnet  may  be  a  natural  one,  as  lodestone,  or 
an  artificial  one.  Artificial  magnets  are  either  per- 
manent or  temporary. 

The  ends  of  a  magnet  are  called  the  poles.  The 
end  which  points  to  the  north  when  the  magnet  is 
freely  suspended  is  the  north,  marked,  or  +  pole, 
while  that  which  points  to  the  south  is  the  south,  un- 
marked, or  -  pole. 

Magnetic  Field. — When  a  bar  magnet  is  placed 
beneath  a  sheet  of  paper  on  which  are  some  iron 


8  A  MANUAL  OF  X-RAY  TECHNIC 

filings,  the  filings  will  arrange  themselves  in  lines 
radiating  from  each  pole  of  the  magnet  as  shown  in 
Fig.  4.  The  area  surrounding  any  magnetic  body  is 
called  a  magnetic  field;  it  is  the  space  through  which 
the  magnetic  force  acts.  The  lines  of  force  are  sup- 
posed to  flow  from  the  north  to  the  south  pole  outside 
of  the  magnet  and  in  the  opposite  direction  inside, 
making  a  complete  circuit. 


Fio.  4. — Action  of  bar  magnet  on  iron  filings. 

Electro-magnetism. — It  can  be  shown  experi- 
mentally that  an  electric  current  has  magnetic  proper- 
ties ;  it  will  deflect  the  magnetic  needle  and  will  cause 
iron  filings  to  arrange  themselves  as  they  do  when 
placed  in  the  field  of  a  magnet. 

A  coil  of  wire  through  which  a  current  is  passing 
is  called  a  solenoid  and  has  all  the  properties  of  a 
magnet  (Fig.  5) .  An  electro-magnet  is  a  bar  of  iron 
magnetized  by  an  electric  current  passing  through  a 
coil  of  wire  surrounding  it  (Fig.  6). 


ELECTRICITY  AND  MAGNETISM 


The  strength  of  an  electro-magnet  is  directly  pro- 
portional to  the  strength  of  the  current  passing 
through  the  wire  surrounding  it,  and  to  the  number 
of  turns  of  the  wire.  Since  electric  currents  may  be 
made  very  strong  and  since  we  may  use  as  many  turns 
of  wire  as  desired,  it  becomes  possible  to  make 
electro-magnets  of  enormous  strength. 


Fig.  6. — Electro-magnet. 

Just  as  a  current  may  be  induced  in  one  of  two 
wires  lying  near  each  other  by  increasing  or  decreas- 
ing the  strength  of  the  current  in  the  other  wire,  in 
the  same  manner  a  current  may  be  induced  in  a  coil 
of  mre  surrounding  an  electro-magnet  but  insulated 
from  it.  Upon  this  fact  depends  the  action  of  induc- 
tion coils,  transformers,  and  motor  generators,  all  of 
which  are  used  in  X-ray  work. 


CHAPTER  II. 

The  X-ray.    History  and  Properties. 

History. — The  first  vacuum  tubes  were  made  by 
G^issler  about  the  year  1858.  The  passage  of  an 
electric  current  through  these  tubes,  which  were  of 
low  vacuum,  caused  a  faint  glow,  varying  in  intensity 
with  the  degree  of  vacuum.  Hittorf  discovered  about 
1860  that  the  stream  of  discharge  in  a  Geissler  tube 
could  be  deflected  by  a  magnet.  It  was  in  1879  that 
Sir  William  Crookes,  experimenting  with  tubes  of 
very  high  vacuum,  discovered  the  cathode  rays.  The 
glow  which  is  present  in  the  tubes  of  low  vacuum  has 
disappeared  in  these  high  vacuum  tubes  and  is  re- 
placed by  a  greenish  fluorescence  of  the  walls  of  the 
tube.  To  this  form  of  radiant  energy  Crookes  gave 
the  name  of  cathode  rays. 

The  study  of  the  discharge  in  high  vacuum  tubes 
was  continued  by  many  investigators,  prominent 
among  whom  were  Professor  Hertz  and  his  assistant 
Professor  Lenard.  In  1894  Lenard  proved  that  the 
cathode  rays  caused  phenomena  outside  of  the  tube, 
for  experimenting  with  a  tube  having  a  sheet  of 
aluminum  in  the  end  opposite  to  the  cathode  he 
observed  that  the  radiation  which  passed  through  the 
aluminum  could  cause  fluorescence  in  such  substances 

10 


THE  X-RAY.    HISTORY  AND  PROPERTIES       11 

as  platino-barium  cyanide.  The  next  year,  1895, 
Prof.  William  Conrad  Rontgen,  at  Wiirzburg,  was 
experimenting  with  a  high  vacuum  tube  covered  with 
black  paper  impervious  to  ordinary  light.  He  noticed 
that  a  near-by  paper  covered  with  platinobarium 
cyanide  fluoresced  brilliantly  while  the  tube  was  in 
action.  Rontgen  realized  that  this  phenomenon  must 
be  caused  by  some  hitherto  unrecognized  force,  differ- 
ing essentially  from  the  cathode  rays.  Continuing  his 
experiments  Rontgen  found  that  he  could  obtain 
shadow  pictures  on  photographic  plates  of  metallic 
objects  in  a  box  which  was  impervious  to  light,  and 
also  of  the  bones  of  the  hand.  He  soon  made  his  dis- 
covery public  and  it  was  only  a  short  time  until  the 
use  of  the  rays  became  general  for  diagnosis,  and  not 
long  until  valuable  therapeutic  effects  were  also 
observed. 

The  Cathode  Rays. — These  rays  are  formed  at 
the  cathode  of  high  vacuum  tubes  and  are  believed  to 
be  streams  of  electrified  molecules  shot  off  from  the 
cathode.  They  have  the  following  properties:  (1) 
they  can  be  deflected  by  a  magnet;  (2)  they  cause 
fluorescence  and  phosphorescence  of  certain  sub- 
stances; (3)  they  affect  photographic  plates  like 
ordinary  light;  (4)  they  have  no  known  effect  on  the 
bodily  tissues. 


12  A  MANUAL  OF  X-RAY  TECHNIC 

The  Relation  of  the  Cathode  Rays  to  X-rays. 
— The  X-ray  is  formed  at  the  point  of  impact  of  the 
cathode  ray  upon  any  solid  object. 

X-rays  themselves  are  believed  to  be  due  to  some 
disturbance  in  the  ether  and  to  be  true  rays.  They 
have  the  following  properties:  (1)  they  are  not  de- 
flected by  a  magnet;  (2)  they  are  invisible  but  cause 
fluorescence  and  phosphorescence  of  certain  sub- 
stances; (3)  they  aff*ect  photographic  plates  like 
ordinary  light ;  { 4 )  they  travel  in  straight  lines, — can- 
not be  reflected  or  refracted;  (5)  they  will  pass 
through  all  known  substances  with  varying  degrees 
of  intensity;  (6)  they  cause  the  air  to  become  a  con- 
ductor and  consequently  cause  the  discharge  of  elec- 
trically charged  bodies;  (7)  they  have  marked  efl'ects 
on  the  bodily  tissues. 


CHAPTER  III. 

Apparatus  for  the  Production  of  X-rays. 

The  apparatus  necessary  for  the  production  of  X- 
rays  consists  of  suitable  vacuum  tubes,  and  of  some 
form  of  installation  for  the  production  of  suitable 
currents  (static  machine,  induction  coil,  or  trans- 
former). 

VACUUM  TUBES. 

The  eai-liest  forms  of  vacuum  tubes  were  the 
Geissler  tubes.  These  are  of  low  vacuum  and  trans- 
mit electric  currents  more  readily  than  air.  During 
such  passage  the  tube  lights  up  with  a  soft  luminous 
glow.  As  the  tube  is  still  further  exhausted  the 
current  passes  with  greater  difficulty  and  the 
luminous  glow  is  replaced  by  a  greenish  fluorescence 
of  the  walls  of  the  tube.  When  it  reaches  this  de- 
gree of  vacuum  it  is  known  as  a  Crookes  tube  and  in 
it  are  produced  the  cathode  rays.  These  in  turn  give 
rise  to  the  X-ray  wherever  they  strike  any  solid  object. 

The  first  X-ray  tubes  were  somewhat  conical  in 
shape,  the  cathode,  which  was  a  flat  disc,  being  placed 
in  the  small  end  (Fig.  7).  The  cathode  rays  were 
thus  thrown  upon  the  opposite  end  of  the  tube,  the 
anode  being  ring-shaped  so  as  not  to  obstruct  the 
passage  of  the  rays. 

IS 


14 


A  MANUAL  OF  X-RAY  TECHNIC 


A  great  advance  was  made  when  Herbert  Jackson 
devised  a  tube  with  a  metallic  target  fixed  within  it  at 
or  near  the  focus  point  of  the  cathode  stream  (Fig.  8) . 
This  "  focus  "  tube  has  undergone  many  modifica- 
tions, among  which  the  most  important  were  the  addi- 
tion of  an  accessory  anode,  and  of  a  device  to  regulate 
the  vacuum. 

A  late  model  X-ray  tube  is  one  in  which  the  air 


Fia.  7. — Early  type  of  X-ray  tube. 

has  been  exhausted  by  means  of  mercury  pumps  to 
about  one-millionth  of  an  atmosphere.  The  essential 
parts  of  the  tube  are  the  cathode,  the  anti-cathode  or 
target,  the  accessory  anode,  and  some  device  to  regu- 
late the  vacuum  ( Fig.  9 ) . 

The  cathode  of  a  focus  tube  is  made  of  aluminum, 
because  this  metal  does  not  suiFer  disintegration  with 
consequent  discoloration  of  the  walls  of  the  tube.    The 


APPARATUS  FOR  PRODUCTION  OF  X-RAYS      15 

concave  form  of  the  cathode  causes  the  cathode  rays  to 
be  focussed  upon  a  point  on  the  target,  or  anti-cathode, 
as  it  is  called. 


Fig.  8. — Jackson's  foous  tube. 


As  tubes  are  now  constructed,  the  target  is  always 
an  anode  of  the  tube,  but  it  is  not  necessarily  so.  The 
target  is  usually  made  of  platinum,  because  the  intense 


Fig.  9. — Modern  type  of  X-ray  or  focus  tube.     1,  cathode;  2,   target;  3,  accessory 
anode;  4,  vacuum  regulator;  5,  adjustable  wire;  6,  X-ray  hemisphere. 

heat  generated  at  the  point  of  impact  of  the  cathode 
stream  requires  a  metal  whose  fusing  point  is  very 
high.     Even  platinum  is  not  entirely  infusible  and 


16  A  MANUAL  OF  X-RAY  TECHNIC 

often  melts  under  the  intense  heat  generated.  Iridium 
and  osmium  have  been  used  to  some  extent,  and  tubes 
are  now  being  made  with  tungsten  targets.  The  latter 
bids  fair  to  entirely  replace  platinum  for  this  purpose. 
The  target  is  usually  surrounded  by  a  heavy  block  of 
some  metal,  such  as  copper,  which  is  a  good  conductor 
of  heat.  As  an  additional  precaution  against  fusing, 
the  target  is  often  placed  at  a  point  just  beyond  the 
mathematical  focus  of  the  tube.  Water-cooled  tubes, 
in  which  a  colunm  of  water  is  sealed  in  a  tube  sur- 
rounding the  anti-cathode,  or  allowed  to  flow  through 
it,  are  also  used  to  prevent  fusing  of  the  target.  If 
certain  defects,  such  as  the  danger  of  breakage,  could 
be  overcome  in  these  tubes  they  would  be  ideal  for  X- 
ray  work.  The  target  is  placed  obliquely  to  the  axis 
of  all  X-ray  tubes  so  that  the  greater  part  of  the  X- 
rays  are  thrown  out  at  one  side. 

The  accessory  anode  is  made  of  aluminum.  It  is 
connected  to  the  anti-cathode  by  a  wire  outside  of  the 
tube.  Tubes  furnished  with  an  accessory  anode  do 
not  increase  in  resistance  so  rapidly  as  do  those  of 
older  models. 

Regulatestg  the  Vacuum  in  the  Focus  Tube. 
— The  tendency  of  the  X-ray  tube  to  increase  in  re- 
sistance, making  it  increasingly  difficult  for  the 
current  to  pass  through  it,  has  caused  the  introduction 
of  many  contrivances  for  lowering  the  vacuum  when 


APPARATUS  FOR  PRODUCTION  OF  X-RAYS      17 

it  has  become  too  high.  One  of  these  was  the  osmo- 
regulator  of  Villard.  It  consisted  of  a  platinum  pin 
sealed  into  the  tube  with  one  end  projecting  outside. 
Heating  the  projecting  end  with  a  flame  caused  the 
platinum  to  become  porous  and  to  absorb  hydrogen, 
thus  lowering  the  vacuum  of  the  tube. 

Baking  a  tube  in  an  oven  at  200°  to  300°  F.  for 
several  hours  will  also  lower  the  vacuum. 


Fio.  10. — Queen's  self-regulating  tube. 


In  1896  Queen's  self -regulating  tube  came  into  use 
(Fig.  10) .  This  tube  had  a  relatively  large  accessory 
bulb  B  in  which  was  sealed  a  smaller  bulb  h,  the  latter 
containing  some  chemical  such  as  potassium  chlorate. 
The  smaller  bulb  connected  directly  with  the  main 
bulb.  When  the  vacuum  in  the  main  bulb  was  too 
high  the  current  could  no  longer  pass  directly  through 
the  tube  but  sparked  across  the  path  of  less  resistance 


18  A  MANUAL  OF  X-RAY  TECHNIC 

from  the  cathode  C  to  the  end  of  the  adjustable  wire 
W,  causing  the  potassium  chlorate  in  the  small  bulb 
to  become  heated.  The  vapor  given  off  into  the  tube 
from  the  potassium  chlorate  lowered  the  vacuum  in 
the  main  bulb  until  the  current  could  pass  directly 
through,  when  the  sparking  from  the  cathode  to  the 
adjustable  wire  ceased. 

The  regulating  device  most  largely  used  at  present 
is  one  in  which  the  accessory  tube  connects  directly 
with  the  main  bulb  (Fig.  9).  Asbestos  is  the  sub- 
stance usually  used  instead  of  the  chemical  of  the  old 
Queen  tube.  When  the  current  sparks  across  from 
the  cathode  to  the  adjustable  wire,  air  is  forced  out 
of  the  interstices  of  the  asbestos  and  the  vacuum  con- 
sequently lowered.  Instead  of  using  the  adjustable 
wire  on  the  tube  the  regulating  device  may  be  con- 
nected by  a  third  wire  to  an  adjustable  spark  gap  on 
the  coil  or  transformer.  This  is  the  most  convenient 
method  since  it  enables  the  operator  to  regulate  the 
vacuum  from  a  distance. 

When  new  tubes  are  ordered  it  is  necessary  to 
specify  whether  they  are  to  be  used  with  a  coil  or  a 
transformer,  since  tubes  pumped  for  use  with  a  coil 
are  of  too  high  vacuum  for  use  with  a  transformer. 

When  a  new  tube  is  received  it  is  usually  found  to 
be  of  relatively  low  vacuum,  but  after  being  used  a 
few  times  it  reaches  its  point  of  maximum  usefulness. 


APPARATUS  FOR  PRODUCTION  OF  X-RAYS      19 

The  vacuum  then  seems  to  remain  about  stationary 
for  some  time  and  then  gradually  increases  until  it 
reaches  a  point  where  it  must  be  lowered  every  time  it 
is  used.  Finally  the  vacuum  becomes  so  high  that  it 
can  no  longer  be  lowered  sufficiently  to  allow  the 
current  to  pass. 

Directions  for  Regulating  the  Vacuum. — ^If 
the  current  cannot  pass  through  the  tube  on  account 
of  the  high  vacuum  it  sparks  across  between  the 
positive  and  negative  terminals  of  the  coil  or  trans- 
former. An  adjustable  spark  gap  is  provided  so 
that  the  operator  may  measure  the  length  of  the 
spark.  The  length  of  spark  that  a  tube  will  "  back- 
up "  is  a  measure  of  the  resistance  of  that  tube. 

If  the  tube  is  too  high  to  allow  the  current  to  pass 
when  the  latter  is  at  its  full  strength,  the  end  of  the 
adjustable  wire  should  be  placed  at  a  distance  of  about 
two  inches  from  the  cathode  (never  touching  it)  and 
the  weakest  current  possible  allowed  to  spark  across 
to  the  regulator.  The  wire  is  then  moved  to  a  distance 
of  five  or  six  inches  from  the  cathode  and  the  current 
turned  on  to  its  full  strength.  This  process  is  re- 
peated until  the  tube  lights  up  properly  and  there  is 
no  sparking  at  the  parallel  spark  gap.  The  same 
method  is  followed  when  the  adjustable  regulating 
spark-gap  on  the  apparatus  is  used  instead  of  the 
adjustable  wire  on  the  tube.     Great  care  must  be 


20  A  MANUAL  OF  X-RAY  TECHNIC 

exercised  in  this  matter  of  lowering  the  vacuum  of  a 
tube  for  it  is  exceedingly  easy  to  lower  it  to  such  an 
extent  as  to  render  it  valueless  until  it  is  re-pumped. 
If  a  strong  current  is  used  for  regulating  it  will  cause 
a  thick  yellow  spark  to  jump  across  and  probably  de- 
stroy the  vacuum. 

To  increase  the  vacuum  of  a  tube  a  weak  current 
may  be  run  through  it  in  a  reverse  direction  for 
several  times.  If  this  is  done  every  day  for  consider- 
able time  the  tube  becomes  higher.  A  tube  will  also 
increase  in  resistance  by  constant  use. 

An  X-ray  tube  is  said  to  be  soft  when  the  vacuum 
is  low  and  hard  when  it  is  high.  The  penetrative 
power  of  the  rays  increases  with  the  degree  of  vacuum 
\  and  with  the  strength  of  the  current. 

When  working  well  the  tube  shows  a  well-marked 
hemisphere  of  greenish  fluorescence  in  front  of  the 
target,  while  the  part  of  the  tube  behind  the  target  is 
dark. 

Secondary  Rays  or  Sagnac  Rays. — These  are 
rays  given  off  when  the  X-ray  strikes  an  object,  as 
parts  of  the  apparatus  or  tissues  of  the  body.  They 
pass  in  all  directions  and  may  blur  the  radiogram; 
they  may  even  pass  through  the  plate  in  the  wrong 
direction. 

Indirect  Rays. — These  are  rays  formed  at  the 
extremities  of  the  arc  and  are  useless  for  radiography. 


APPARATUS  FOR  PRODUCTION  OF  X-RAYS     21 

The  useful  rays  are  those  which  come  off  at  right 
angles  from  the  target.  The  use  of  a  diaphragm  with 
a  circular  aperture  eliminates  most  of  the  indirect 
rays,  and  also  much  of  the  secondary  radiation. 

Means  of  Determining  the  Intensity  or 
Penetrative  Power  of  the  X-rays. —  ( 1 )  Appear- 
ance of  the  Tube:  In  a  tube  of  low  vacuum  the  green- 
ish fluorescence  is  soft  and  somewhat  yellowish  and 
the  tube  is  not  so  distinctly  divided  into  hemispheres. 
There  is  also  a  bluish  color  just  in  front  of  the 
cathode,  and  if  the  vacuum  is  very  low  a  blue  line 
may  be  seen  extending  from  the  cathode  to  the  target. 
In  the  tube  of  high  vacuum  the  fluorescence  is  of  a 
bright  green  color  and  the  tube  is  divided  into  two 
distinct  hemispheres.  (2)  Fluoroscopy ■'  Using  the 
fluoroscope  and  some  object  such  as  a  skeleton  hand 
as  an  indicator.  It  is  very  dangerous  for  the  operator 
to  use  his  own  hand  because  of  the  liability  to  X-ray 
dermatitis  and  its  sequels.  (3)  The  Spark  Gap:  The 
length  of  the  spark  that  a  tube  "  backs  up  "  varies 
with  the  strength  of  the  current  as  well  as  with  the 
resistance  of  the  tube,  but  if  taken  in  conjunction 
with  the  reading  of  the  milliamperemeter  it  is  a  good 
indication  of  the  penetrative  power.  (4)  The  milli- 
ammeter:  The  reading  of  the  milliammeter  also 
varies  with  the  strength  of  current  and  resistance  of 


22  A  MANUAL  OF  X-RAY  TECHNIC 

tube.  It  must  be  remembered  that  a  high  reading 
does  not  necessarily  mean  a  tube  of  high  penetration. 
Indeed  it  more  often  means  just  the  opposite.  The 
lower  the  tube  the  greater  the  amount  of  current  that 
can  pass  through  and  consequently  the  higher  the 
reading  of  the  milliammeter.  But  if  the  tube  gives 
a  spark  of  four  and  a  half  to  six  inches  in  length,  and 
at  the  same  time  the  milliammeter  has  a  high  reading, 
then  the  degree  of  penetration  is  great.  (5)  The 
radiochromometer  of  Benoist:  The  construction  of 
this  instrument  is  based  upon  the  fact  that  different 
metals  vary  in  their  penetrability  to  the  X-ray.  A 
silver  disk  0.11  mm.  in  thickness  placed  in  the  centre 
of  the  device  is  used  as  the  standard  of  comparison. 
Round  this  centre  are  placed  layers  of  aluminum  of 
varying  thickness.  The  diaphragm  is  rotated  until 
the  tint  of  the  sector  corresponds  to  that  of  the  centre, 
when  it  is  read  off,  as  No.  1,  2,  3,  4,  etc.,  Benoist. 

For  radiographic  work  the  length  of  the  spark 
gap  and  the  reading  of  the  milliammeter  taken  to- 
gether probably  afford  the  most  practical  and  best 
method  of  determining  the  degree  of  penetration. 

Care  of  the  X-ray  Tube. — It  is  necessary  to 
take  certain  precautions  in  using  focus  tubes  in  order 
to  keep  them  at  the  point  of  maximum  usefulness  for 
the  longest  possible  time.    In  cold  weather  the  tube 


APPARATUS  FOR  PRODUCTION  OF  X-RAYS     23 

should  be  warmed  before  use.  When  hot  it  should  not 
be  allowed  to  cool  off  too  suddenly.  The  lead  wires 
ought  not  to  come  in  contact  with  the  tube  when  in 
action,  since  a  spark  may  jump  across  to  the  glass 
and  cause  puncture.  Keep  tubes  perfectly  clean;  a 
small  particle  of  dust  may  attract  the  current  and 
cause  puncture.  New  tubes  are  likely  to  be  rather 
unstable  in  vacuum  and  should  be  used  cautiously 
with  weak  currents,  and  with  very  short  exposures 
with  strong  currents,  until  they  become  seasoned. 
Avoid  overheating  the  tube  by  too  long  or  too  fre- 
quent use.  The  place  of  greatest  heating  is  around 
the  cathode,  and  it  is  here  that  the  greatest  number  of 
punctures  occur. 

Means  of  Determining  the  Positive  and 
Negative  Terminals. — In  order  to  connect  the  X- 
ray  tube  properly  it  is  necessary  to  know  which  is  the 
positive  and  which  the  negative  terminal  of  the 
apparatus  from  which  the  current  is  being  taken. 
This  may  be  determined  in  the  following  ways:  (1) 
On  the  induction  coil  or  transformer  the  left  hand 
side  is  usually  the  positive  pole;  (2)  if  both  poles  are 
immersed  in  water,  bubbles  arise  from  the  negative; 
(3)  the  negative  pole  ionizes  a  solution  of  potassium 
iodide,  turning  the  solution  red  around  this  pole  by 
liberating  free  iodine;  (4)  the  spark  at  the  negative 


24  A  MANUAL  OF  X-RAY  TECHNIC 

pole  is  thick  and  white,  while  that  at  the  positive  is 
thin  and  wiry;  (5)  when  the  tube  is  properly  con- 
nected, the  anode  to  the  positive  terminal  and  the 
cathode  to  the  negative,  the  tube  lights  up  in  the 
normal  manner  with  well-marked  hemispheres,  while 
if  the  current  is  passing  through  in  the  opposite 
direction  rings  of  light  are  seen  extending  around  the 
tube  in  many  different  directions. 


CHAPTER  IV. 

Apparatus  for  Exciting  the  X-ray  Tube, 
static  machine  and  induction  coil. 

The  apparatus  used  to  excite  X-ray  tubes  may  be 
a  static  machine,  an  induction  coil,  or  a  high  potential 
transformer. 

The  static  machine  is  now  httle  used  for  X-ray 
work,  its  use  being  confined  to  radiotherapy.  It  gives 
a  very  uniform  discharge  at  exceedingly  high  voltage, 
but  the  amperage  is  so  low  as  to  necessitate  unduly 
long  exposures  for  radiographic  work. 

the  INDUCTION  COIL. 

An  induction  coil  consists  of  a  core  of  soft  iron 
.wire  upon  which  is  wound  a  primary  coil  of  coarse 
wire.  Upon  the  primary  coil,  carefully  insulated 
from  it,  is  wound  the  secondary  coil.  The  latter  is 
made  up  of  very  many  turns  of  fine  wire,  while  the 
primary  consists  of  relatively  few  turns  of  coarse 
wire.  A  current  is  passed  thi'ough  the  primary  wind- 
ing and  magnetizes  the  iron  core,  thus  setting  up  a 
strong  magnetic  field  through  and  around  the  second- 
ary winding.  The  current  in  the  primary  is  made  to 
vary  rapidly  in  strength  by  means  of  some  form  of 

25 


26  A  MANUAL  OF  X-RAY  TECHNIC 

interrupter,  thus  producing  rapid  changes  in  the  in- 
tensity of  the  magnetic  field.  This  reacts  upon  the 
windings  of  the  secondary  and  induces  an  electro- 
motive force  in  each  turn  of  the  wire.  At  each  make 
of  the  current  in  the  primary  coil  a  weak  current  flow- 
ing in  the  opposite  direction  is  set  up  in  the  secondary ; 
while  at  each  break  in  the  current  there  is  induced  in 
the  secondary  a  strong  current  flowing  in  the  same 
direction.  This  break  current  is  the  one  used  to  ex- 
cite the  X-ray  tube.  If  the  make  current  is  allowed 
to  pass  into  the  tube  "  inverse  rays  "  are  produced 
and  the  efficiency  of  the  ray  is  greatly  reduced. 


c^Lf  ID  (  )^ 

Fig.  11. — The   oscilloscope. 

Inverse  Currents. — ^A  tube  in  which  the  inverse 
current  plays  a  part  does  not  have  the  clear-cut 
hemispheres  of  a  properly  working  tube,  but  will  have 
one  or  more  green  rings  back  of  the  target. 

The  production  of  inverse  currents  can  also  be 
demonstrated  by  means  of  the  oscilloscope  (Fig.  11). 
When  connected  in  series  with  a  coil,  if  the  current  is 
unidirectional  a  violet  band  will  be  seen  at  the  negative 
end,  while  if  there  are  inverse  currents  bands  of  equal 
or  unequal  length  will  be  seen  at  both  ends. 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       27 

Inverse  currents  may  be  prevented  from  entering 
the  tube  by  introducing  a  spark-gap  of  such  length 
that  the  make  current  is  too  weak  to  pass  it. 

Another  method  is  to  use  the  ventril  or  valve  tube 
of  Villard  (Fig.  12).  One  pole  of  the  Villard  tube 
is  made  of  a  spiral  of  aluminum  giving  a  large  sur- 
face. This  pole  acts  well  as  a  cathode  and  permits 
currents  to  pass  readily  when  it  is  the  negative  pole. 


FiQ.  12.— Valve  tube. 


As  stated  above,  the  secondary  of  the  induction 
coil  consists  of  many  windings  of  very  fine  wire  some- 
times ten  miles  or  more  in  length.  It  is  usually  wound 
in  sections  and  these  subsequently  assembled.  All  the 
layers  of  the  coil  must  be  thoroughly  insulated,  each 
from  the  other. 

The  effect  of  the  induction  coil  is  to  change  a 
current  of  relatively  low  potential   (110  volts)   and 


28  A  MANUAL  OF  X-RAY  TECHNIC 

high  amperage  (5-25)  to  a  current  of  very  high 
potential  (100,000  to  150,000  volts)  but  of  corre- 
spondingly low  amperage. 

THE  INTERRUPTER. 

Some  means  of  interrupting  the  current  must  be 
supplied  with  the  induction  coil,  for  it  is  only  by  vary- 
ing the  number  of  lines  of  force  surrounding  the 
primary  winding  that  a  current  can  be  set  up  in  the 
secondary. 

Interrupters  may  be  classified  as  follows: 

(1)  Mechanical. 

(a)   Vibrating.    This  is  the  slowest. 
(6)  Mercury.    Medium  rate. 

1.  Dipper. 

2.  Rotary. 

3.  Jet. 

(2)  Electrolytic.    Most  rapid  and  there- 
fore give  the  strongest  current. 

1.  Wehnelt. 

2.  Caldwell- Simon. 
Vibrating  Interrupter. — This  interrupter  oper- 
ates on  the  same  principle  as  the  electric  bell,  and 
consists  essentially  of  a  spring  carrying  at  its  end  a 
platinum  contact  point  and  an  armature  of  soft  iron. 
The  armature  is  close  to  the  end  of  the  induction  coil. 
The  instant  a  current  flows  through  the  primary  of 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       29 

the  coil  the  core  becomes  magnetized,  and  acting  upon 
the  armature  of  soft  iron  pulls  the  platinum  contact 
point  away  from  its  contact  with  the  general  circuit. 
When  this  happens  the  circuit  is  of  course  broken  and 
the  core  becomes  demagnetized.  The  armature  is  no 
longer  held  against  the  core  and  the  spring  carries 
the  platinum  contact  point  back  to  its  contact  with 
the  main  circuit. 

There  are  many  modifications  of  the  vibrating 
interrupter  and  in  some  form  or  other  it  has  been 
very  widely  used  with  X-ray  apparatus,  but  there  are 
many  objectionable  features  to  all  of  them.  The 
platinum  points  may  become  uneven  or  may  fuse,  the 
spring  may  break,  and  they  are  very  noisy.  They  are 
still  used  to  some  extent  with  portable  apparatus  but 
practically  never  with  stationary  installations.  It  is 
quite  probable  also  that  the  portable  apparatus  of  the 
future  will  be  some  form  of  high  potential  trans- 
former actuated  by  a  gas  engine,  with  which  an  inter- 
rupter is  unnecessary. 

Mercury  Interrupters. — These  give  a  medium 
rate  of  make  and  break  and  medium  strength  of 
current. 

Dipper  Mercury  Interrupter. — The  contacts  are 
made  by  a  metallic  rod  dipping  into  the  mercury.  The 
mercury  should  be  covered  with  a  layer  of  some  non- 


30  A  MANUAL  OF  X-RAY  TECHNIC 

conducting  substance  such  as  paraffin  or  alcohol  so  as 
to  effectually  prevent  sparking.  The  shaft  raising 
and  lowering  the  metallic  rod  is  operated  by  a  motor 
connected  with  a  shunt  circuit. 

Rotary  Mercury  Interrupter. — This  consists  of  a 
turbine  attached  to  a  shaft  which  is  rotated  by  a 
motor.  There  are  platinum  tips  on  the  turbine  and 
the  interruptions  are  made  by  these  entering  and 
leaving  the  mercury. 

The  rate  of  interruptions  with  both  of  these  inter- 
rupters is  regulated  by  varying  the  speed  of  the 
motor. 

Jet  Mercury  Interrupters. — A  motor  operates  a 
pump  which  throws  jets  of  mercury  in  opposite  direc- 
tions. These  jets  striking  the  armatures  produce  the 
contacts.  By  raising  or  lowering  the  armatures  the 
strength  of  the  current  may  be  increased  or  decreased. 

Electrolytic  Interrupters.  —  These  inter- 
rupters depend  upon  the  fact  that  when  a  current  of 
electricity  is  passed  through  a  liquid  and  one  of  the 
metallic  electrodes  is  very  small  the  surface  of  this 
electrode  becomes  covered  with  a  thin  layer  of  gas 
which  stops  the  flow  of  the  current.  As  soon  as  the 
current  stops  the  gas  disappears  and  the  current  again 
flows.  These  interrupters  give  as  high  as  40,000 
breaks  per  minute. 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       31 

The  Wehnelt  Interrupter  (Fig.  13).— The  fluid 
in  this  interrupter  is  sulphuric  acid  diluted  with  six 


SiSMT  I 


nCOMUVtOH    INVERTED  V-SH/WO 

opcNiN*  THiv  jHovio  ar  cmuho 

OOtlN  OK   ASNErrCO 

Pl^TlMlM  POrNT  MUST  »|T  ^il»i.y 


>  ^^ThE  J»f«fT«  »  eietvES  rtBI 

>  --SVtlSfD  |)N  Mait  (XirfITi  OWLV. 
,  y  TMI  iM«»T  eOMPlCTCS  THf  CIH 
6     y    CMT   fROM  fHI  SWITCH   BonM 

^/  ,  r»The  Pi/ttiwuM  electromj 

^SOT'MENUMO  INDtPfNOEM  OF 
'  JTHI  rilBlS  THC  •UeSEX  KNttS      ' 

^K  PlKtt  Oldtcnv  OM       ' 


t«*» 


Ui 


;C«^ 


Fig.  13. — The  Wehnelt  electrolytic  interrupter. 

times  as  much  water.  The  small  electrode  is  of  plati- 
num, and  the  large  one  of  lead.  The  platinum  rod  is 
enclosed  in  a  porcelain  sheath  and  by  means  of  a 


32  A  MANUAL  OF  X-RAY  TECHNIC 

screw  a  smaller  or  larger  amount  of  the  platinum  may 
be  made  to  project  into  the  liquid.  When  a  small 
amount  projects  the  impulses  are  small  and  rapid, 
and  when  a  larger  amount  projects  they  are  heavier 
and  less  rapid. 

The  Caldwell- Simon  Interrupter. — This  has  two 
large  lead  electrodes  dipping  into  dilute  sulphuric 
acid,  the  vessel  containing  which  is  divided  into  halves 
by  a  vertical  partition.  There  are  very  small  holes 
in  this  partition  and  when  the  current  passes  small 
bubbles  of  vapor  are  formed  in  them.  This  causes 
the  break  in  the  current.  In  this  form  of  interrupter 
either  pole  may  be  the  positive,  while  in  the  Wehnelt 
the  platinum  rod  must  always  form  the  positive  pole. 

The  electrolytic  interrupter  is  the  best  for  radio- 
graphic work  while  a  mercury  interrupter  is  better 
for  fluoroscopy  and  for  radiotherapy. 

SOURCES  OF  CURRENT  FOR  OPERATrNG  AN   INDUCTION 

COIL. 

(1)  Electric  Batteries. — All  forms  of  batter- 
ies are  objectionable  because  of  the  corrosive  solutions 
they  contain,  and  because  of  their  rapid  deterioration. 
They  are  practically  never  used  in  X-ray  work. 

( 2 )  Storage  Batteries. — The  storage  battery  of 
an  electric  automobile  will  operate  a  coil  and  inter- 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       33 

rupter.  Small  portable  storage  batteries  may  also  be 
used.  The  greatest  objections  to  the  use  of  storage 
batteries  for  portable  apparatus  are  their  great  weight 
and  the  difficulties  of  getting  them  charged. 

(3)  Electric  Lighting  and  Power  Circuits. 
— The  110  or  220  volt  lighting  circuit  with  direct 
current  is  the  best  available  source  of  power  for  an 
X-ray  coil.  The  alternating  current  of  the  same 
voltage  is  also  often  used  but  requires  additional 
apparatus  to  render  it  unidirectional.  This  is  de- 
scribed below.  Another  available  source  of  energy 
is  the  500-volt-power  circuit. 

Use  of  Coil  with  Alternating  Current. — 
When  only  an  alternating  current  can  be  obtained  to 
operate  a  coil  some  means  must  be  used  to  render  it 
unidirectional.  It  is  possible  to  use  the  Wehnelt  inter- 
rupter for  this  purpose,  but  the  platinum  pole  being 
the  negative  during  one  phase  of  the  current  gives  it 
an  undesirable  polarity  and  causes  its  rapid  destruc- 
tion. 

The  aluminum  cell  rectifier  is  the  device  usually 
employed  to  rectify  alternating  currents  for  use  with 
X-ray  coils.  This  rectifier  transmits  about  90  per 
cent,  of  the  current  passing  in  one  direction  and 
almost  none  of  that  passing  in  the  other.  The  rectifier 
consists  of  four  glass  jars  containing  a  solution  of 


S4 


A  MANUAL  OF  X-RAY  TECHNIC 


Rochelle  salts  (1  part  water  to  1  part  saturated  solu- 
tion of  Rochelle  salts) .  Each  jar  contains  a  lead  and 
an  aluminum  plate.  The  alternating  current  wires 
are  connected  as  shown  in  Fig.  14.  The  wire  which 
delivers   the   positive   current   is   connected   to   the 


-o- 

■ 

1 

A 

L 

i 

L 
A 

A 

1 

L 
A 

J 

< 

y- 

Fig.  14. — Aluminum  cell  rectifier. 


aluminum  of  two  cells  and  the  negative  wire  comes 
from  the  lead  of  the  other  two  cells.  The  current 
flows  readily  so  long  as  it  is  passing  from  the  lead 
through  the  solution  to  the  aluminum,  but  not  in  the 
opposite  direction,  polarization  preventing  the  flow 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       35 

in  one  direction  while  oiFering  little  obstruction  to 
its  passage  in  the  other. 

There  are  other  forms  of  rectifiers  for  the  alter- 
nating current,  such  as  the  mercury  arc  and  mercury- 
vapor  vacuum  tube  rectifiers,  but  the  one  described 
above  is  the  most  commonly  used  at  the  present  time. 

The  loss  of  power  is  so  great  with  an  alternating 
current  that  the  direct  current  is  always  used  to 
operate  a  coil  if  it  can  be  obtained. 


CHAPTER  V. 

Apparatus  for  Exciting  the  X-ray  Tube 

{Continued) . 

High-tension  Transformers. — The  necessity  for 
using  some  form  of  interrupter,  and  also  a  recti- 
fier in  the  case  of  alternating  currents,  both  contain- 
ing some  liquid,  are  disadvantages  always  encountered 
with  coil  apparatus.  Even  with  the  use  of  these 
appliances  inverse  currents  often  persist  and  cause 
rapid  deterioration  of  tubes,  besides  making  it  diffi- 
cult or  impossible  to  obtain  good  pictures.  For  these 
reasons  and  because  of  its  added  efficiency,  the  type 
of  apparatus  known  as  a  transformer  is  at  present  the 
most  satisfactory  for  exciting  the  X-ray  tube. 

The  transformer  consists  essentially  of  a  primary 
and  a  secondary  coil,  both  surrounding  a  continuous 
soft  iron  core.  The  principle  is  exactly  the  same  as  in 
the  induction  coil.  With  the  latter,  however,  an 
interrupter  must  be  used,  while  in  the  former  an  alter- 
nating current  is  utilized  and  the  interruptions  are 
supplied  directly  from  the  dynamo.  The  voltage  of 
the  secondary  current  depends  upon  the  proportion 
between  the  number  of  turns  of  wire  in  the  secondary 
to  the  number  of  turns  in  the  primary.  If,  for  in- 
stance, the  secondary  coil  has  twice  as  many  turns 

36 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       37 

as  the  primary  then  its  voltage  will  be  twice  as  great 
as  that  of  the  primary.  It  should  be  remembered 
that  the  amperage  undergoes  opposite  variations  at 


Fig.  15. — Ring  type  of  transformer. 


the  same  time.  The  transformer  is  a  step-up  or  step- 
down  transformer,  depending  upon  whether  the 
secondary  has  a  greater  or  less  number  of  turns  than 
the  primary.     For  X-ray  work  the  step-up  trans- 


38  A  MANUAL  OF  X-RAY  TECHNIC 

former  is  necessary.  The  ring  type  of  transformer 
is  illustrated  in  Fig.  15,  showing  the  primary  and 
secondary  coils  surrounding  a  ring-shaped  core  of 
iron.  The  transformer  may  be  of  the  shell  or  jacket 
type,  in  which  the  primary  and  secondary  coils  are 
surrounded  by  laminated  masses  of  iron,  which,  from 
an  electrical  standpoint,  constitute  the  core. 

The  efficiency  of  the  transformer  is  very  high, 
being  about  97  per  cent,  of  the  energy  of  the  primary. 
The  current  furnished  to  the  primary  must  be  an 
alternating  one.  If  only  a  direct  current  is  available 
it  must  be  changed  to  an  alternating  one  by  a  motor 
generator.  Operating  the  generator  necessitates  a 
considerable  loss  of  energy,  from  30  per  cent,  to  50 
per  cent,  being  lost  in  this  manner.  For  this  reason 
an  alternating  current  supply  is  to  be  greatly  pre- 
ferred to  the  direct.  It  is  necessary  to  use  a  motor 
even  with  an  alternating  current,  for  reasons  which 
will  be  explained  later,  but  this  causes  very  little  loss 
of  energy. 

The  220-volt  alternating  current  is  the  ideal  one 
for  operating  a  transformer. 

Thorough  insulation  of  the  primary  and  second- 
ary coils  is  necessary.  Some  makers  bury  the  coils 
in  oil  and  others  use  only  wax  as  insulation.  The 
terminals  of  the  secondary  coil  must  also  be  insulated 
or  separated  to  a  considerable  distance  from  each 
other,  to  prevent  sparking  across. 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       39 


Methods  of  Rectifying  the  Current. — Just  as 
the  current  passing  through  the  primary  of  the  trans- 
former is  an  alternating  one,  so  that  in  the  secondary 
is  of  the  same  character.  Before  this  current  can  be 
used  to  excite  an  X-ray  it  must  be  rendered  uni- 


FiG.   16. — Diagram  of  connections  of  iaterrupterless  apparatus. 

directional  by  some  means.  Ventril  or  valve  tubes, 
previously  described,  have  been  used  for  this  purpose, 
but  most  high-tension  transformers  are  now  provided 
with  some  form  of  mechanical  rectifying  switches. 

Fig.    16    represents    diagrammatically    the    con- 
nections of  the  motor,  transformer  and  rectifying 


40  A  MANUAL  OF  X-RAY  TECHNIC 

switches  of  the  so-called  "  interriipterless  "  apparatus 
used  for  X-ray  work.  A  direct  current  is  furnished 
from  the  line  and  passes  through  the  switch  1,  the  line 
L  to  the  armature  2,  and  the  field  3  of  the  motor 
generator.  From  the  generator  the  current  returns 
through  the  wires  A  and  F  to  the  motor  starter  4,  and 
thence  back  through  the  main  switch  to  the  line.  The 
motor  starter  is  simply  a  resistance  box  and  enables 
one  to  start  the  motor  gradually.  In  the  generator 
the  current  is  changed  to  an  alternating  one,  necessi- 
tating a  considerable  loss  of  power  as  mentioned 
above.  This  alternating  current  is  taken  off  from 
the  collecting  rings  C  by  the  brushes  M,  passes 
through  wire  5  to  the  primary  of  the  transformer, 
through  the  windings  of  the  primary  to  wire  6,  through 
rheostat  to  wire  8,  and  the  switch  7,  back  to  the  collect- 
ing ring  on  the  motor.  This  complete  circuit  con- 
stitutes the  primary  circuit.  The  poles  of  the  second- 
ary coil  are  marked  a  and  h.  As  previously  stated, 
the  current  is  here  an  alternating  one,  just  as  in  the 
primary  winding.  Before  it  can  be  utilized  to  excite 
the  X-ray  tube  it  must  be  rendered  unidirectional, 
this  being  accomplished  by  means  of  the  four  revolv- 
ing arms  15, 15',  16  and  16'.  These  arms  are  mounted 
on  the  same  shaft  as  the  motor,  thus  insuring  that  the 
revolutions  of  the  rectifying  arms  are  synchronous 
with  the  phases  of  the  current  from  the  motor.    This 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       41 

is  the  reason  also  why  a  motor  is  used  even  with  alter- 
nating currents,  for  if  the  current  were  taken  directly 
from  an  alternating  light  or  power  circuit  there 
would  be  no  means  of  accurately  synchronizing  the 
revolutions  of  the  rectifying  switches  with  the  phases 
of  the  primary  current.  The  manner  of  operation  of 
the  revolving  arms  is  as  follows:  When  a  is  the 
positive  pole  of  the  transformer  the  current  passes 
through  wire  10  to  the  metal  collecting  ring  12,  sparks 
across  to  the  end  of  the  copper  wire  on  the  revolving 
arm  15  which  is  then  in  position  to  transmit  it,  sparks 
across  from  this  wire  at  the  other  end  of  15  to  the  metal 
plate  13,  and  passes  through  wire  18  to  the  terminal 
20  which  is  connected  with  the  positive  terminal  of 
the  X-ray  tube.  It  then  passes  through  the  tube  to 
the  negative  terminal  (cathode),  through  20'  and  17 
to  the  metal  plate  14,  sparks  across  to  15'  and  from 
15'  to  the  metal  plate  11,  which  is  connected  with  the 
negative  terminal  h  of  the  transformer.  At  the 
opposite  phase  of  the  current  h  is  the  positive  terminal 
of  the  secondary  and  the  current  is  conveyed  through 
9  to  the  plate  11;  the  shaft  has  now  made  a  quarter 
turn  and  instead  of  15'  being  in  position  to  convey  the 
current,  16'  is  now  in  position;  the  current  therefore 
passes  through  16'  to  the  metal  plate  13'  and  is  con- 
veyed through  wire  21  to  18  and  thence  to  the  positive 


42 


A  MANUAL  OF  X-RAY  TECHNIC 


terminal  of  the  tube,  just  as  it  was  in  the  first  instance 
when  a  was  the  positive  of  the  secondary ;  the  current 
then  returns  through  20',  17,  14,  and  revolving  arm 
16,  to  12  and  thence  to  a,  which  is  at  this  instant  the 
negative  terminal  of  the  secondary.  Thus  both  phases 
of  the  current  are  utilized,  but  it  always  passes 
through  the  tube  in  the  same  direction,  no  inverses 
being  produced. 


Fi08.  17  and  18. — Illustrating  rectification  of  current  by  revolving  discs. 


Instead  of  using  four  revolving  arms  to  rectify 
the  current,  a  revolving  disc  on  which  are  mounted 
two  metal  strips  is  used  in  some  constructions,  to 
secure  a  unidirectional  current.  Figs.  17  and  18 
illustrate  this  method  of  rectification.  JP  is  a  mica 
disc,  G  and  H  the  two  metal  strips.  J  and  K  are  the 
terminals  of  the  secondary  of  the  transformer.    L  and 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       43 


M  represent  the  brushes  which  receive  the  rectified 
current.  In  Fig.  17,  if  1  is  +,  the  current  is  taken 
up  by  the  metal  strip  H  and  passes  out  through  L 
to  the  anode  of  the  tube.  At  the  next  alternation  of 
the  current  the  condition  is  shown  in  Fig.  18.    No. 


2Z0VAC 


v^3_vV 


ST.  M         sr  N 
SWITCH      awiTCN 


o- 

PC 


H  T 


RHEOSTAT 


AM-fierar 


Fio.  19. — Diagram  of  connection9  of  an  "interrupterlesa"  apparatus  operating  on  an 
alternating  current. 

2  is  now  the  positive  and  the  metal  strips  have  assumed 
the  position  shown  by  a  quarter  revolution  of  the 
disc ;  the  current  again  passes  through  L  to  the  anode 
of  the  tube.  The  arrows  show  the  direction  of  flow 
of  the  current  in  each  instance. 


44  A  MANUAL  OF  X-RAY  TECHNIC 

Both  the  system  of  the  four  revolving  arms  and 
that  of  the  single  revolving  plate  have  been  found  in 
practice  to  be  durable  and  efficient. 

Fig.  19  is  a  diagram  of  the  connections  of  an 
"  interrupterless  "  apparatus  operating  on  an  alter- 
nating current.  The  main  current  flows  directly 
from  the  line  through  the  primary  of  the  transformer 
instead  of  through  the  rotary  converter  as  in  the  case 
of  the  direct  current. 

The  two  small  motors,  the  starting  motor  and  the 
synchronous  motor,  serve  simply  to  revolve  the 
rectifying  disc  J  M  K,  the  motors  and  rectifying  disc 
all  being  mounted  on  the  same  shaft.  The  switch 
for  the  starting  motor  S  T  M  is  first  closed,  and  when 
this  motor  has  reached  its  maximum  speed  the  switch 
to  the  synchronous  motor  S  Y  M  is  closed.  The 
shaft  is  then  revolving  at  the  same  rate  as  that  of  the 
dynamo  in  the  power  house  which  is  the  source  of  the 
current.  This  insures  that  the  revolutions  of  the 
rectifying  disc  are  exactly  synchronous  with  the  alter- 
nations of  the  current  passing  from  the  secondary  of 
the  transformer  to  the  terminals  J  and  K. 

REGULATING  THE  CURRENT  ON  COIL  OR  TRANSFORMER. 

Electric  currents  are  controlled  by  means  of  re- 
sistance, the  current  strength  being  equal  to  the 


APPARATUS  FOR  EXCITING  X-RAY  TUBE       45 

electro-motive  force  divided  by  the  resistance  ( Ohm's 
law).  Electrical  resistance  depends  upon  the  ma- 
terial of  which  the  conductor  is  made,  the  diameter 
of  its  cross-section,  its  length,  and  its  temperature. 
Copper  wire  is  one  of  the  best  practical  conductors 
of  electricity,  iron  wire  not  so  good,  and  German 
silver  one  of  the  poorest.  The  latter  is  not  used  at  all 
as  a  conductor  but  is  very  widely  used  as  a  resisting 
medium.  The  resistance  of  a  conductor  is  directly 
proportional  to  its  length  and  inversely  proportional 
to  the  area  of  its  cross-section  or  square  of  its  diameter. 

A  rheostat  is  an  appliance  used  to  vary  the 
strength  of  a  current  by  changing  the  amount  of  the 
resistance.  For  X-ray  apparatus,  rheostats  are 
usually  made  of  a  number  of  coils  of  German  silver 
wire. 

In  Fig.  20  the  dots  represent  contact-points  to 
which  the  movable  arm  may  be  shifted.  Nos.  1  and  2 
are  connected  at  the  bottom,  2  and  3  at  the  top,  and 
so  on.  The  leading-in  current  enters  at  H  and  when 
the  movable  arm  is  set  on  the  first  contact  point  the 
current  passes  through  A,  down  coil  No.  1,  up  coil 
No.  2,  down  No.  3,  and  so  on  until  it  passes  out  at  B. 
Shifting  the  arm  to  the  second  point  eliminates  coil 
No.  1  from  the  circuit  and  reduces  the  amount  of 
resistance,  thus  increasing  the  strength  of  the  current. 


46 


A  MANUAL  OF  X-RAY  TECHNIC 


Resistance  may  thus  be  gradually  reduced  by  shifting 
to  successive  points  until  the  last  one  is  reached  and 

12  3^ 


H    Sr 


Fig.  20.— Rheostat. 


the  current  flows  directly  from  H  through  the  mov- 
able arm  to  B,  the  rheostat  no  longer  being  in  the 
circuit. 


CHAPTER  VI. 

Radiography. 

The  X-ray  acts  upon  sensitized  plates  like  ordi- 
nary light,  therefore  the  making  of  radiographs  has 
much  in  common  with  photography.  It  must  always 
be  remembered,  however,  that  whereas  the  photo- 
graph is  produced  by  the  action  of  light  which  is  re- 
flected from  the  object  to  be  photographed,  the  radio- 
gram, on  the  other  hand,  is  a  record  of  the  penetra- 
bility of  the  different  parts  of  the  object  to  the  X-ray. 

The  photographic  plate  consists  of  a  piece  of 
glass  coated  with  gelatin  containing  sensitive  silver 
salts.  The  salt  may  be  either  the  bromide,  the  chlo- 
ride, or  the  iodide  of  silver.  The  iodide  is  not  often 
used  except  occasionally  as  an  addition  to  the 
bromide,  and  the  chloride  is  used  only  for  slow  emul- 
sions such  as  are  used  on  printing-out  paper  and  for 
lantern  slides.  The  gelatin-bromide  emulsion,  either 
with  or  without  the  iodide,  is  the  one  usually  em- 
ployed. The  sensitiveness  of  the  emulsion  is  governed 
by  the  manufacturer  by  the  length  of  time  during 
which  it  is  subjected  to  boiling  or  other  method  of 
"  ripening."  The  increase  of  sensitiveness  is  said  to 
be  due  to  the  enlargement  of  the  particles,  something 
like  the  growth  of  particles  by  crystallization.     The 

47 


48  A  MANUAL  OF  X-RAY  TECHNIC 

particles  as  they  become  larger  are  able  to  absorb 
more  light  and  consequently  a  greater  amount  of 
silver  is  reduced,  rendering  the  plate  more  rapid.  A 
similar  explanation  is  given  as  to  why  the  amount  of 
emulsion  on  the  plate  affects  its  sensitiveness. 

X-ray  plates  differ  from  photographic  plates  only 
in  their  greater  sensitiveness,  the  emulsion  being 
thicker  than  on  photographic  plates. 

The  exact  effect  that  light  has  on  silver  salts  is 
not  yet  entirely  understood.  So  far  as  known,  light 
exerts  a  reducing  effect  on  the  salt,  setting  free  the 
chlorine,  bromine,  or  iodine.  The  latent  image  con- 
sists of  some  modification  of  the  halogen. 

In  order  to  bring  out  the  latent  image  some  form 
of  developer  is  necessary.  A  developer  contains 
several  ingredients  known  respectively  as  the  reducer, 
the  accelerator,  the  restrainer,  and  the  preservative. 
There  are  a  great  variety  of  reducing  agents,  among 
which  are  pyrogallic  acid,  hydroquinon,  metol,  amidol, 
eikonogen,  ortal,  rodinal,  etc.  The  function  of  the 
reducer  is  to  reduce  the  exposed  silver  bromide  to 
metallic  silver,  for  it  is  this  metallic  silver  that  pro- 
duces the  lines  of  the  picture.  Most  of  the  reducers 
named,  however,  will  not  act  quickly  enough  by  them- 
selves, so  that  an  accelerator  must  be  added.  Some 
alkali,  usually  sodium  carbonate,  fulfills  this  function. 

The    restrainer    is    added,    usually    potassium 


RADIOGRAPHY  49 

bromide,  so  that  the  developing  may  be  more  under 
control  and  not  take  place  too  rapidly.  Sodium 
sulphite  is  usually  added  to  act  as  a  preservative, 
which  it  does  by  taking  up  oxygen  and  thus  prevent- 
ing oxidation  of  the  reducer. 

Following  are  some  formulas  for  developing 
solutions : 

HYDROQUINON  OR  QUINOL. 

No.   1.  Hydroquinon 6      gm. 

Sodium  sulphite 50      gm. 

Water 500      c.c. 

No.  2.  Potassium  carbonate  ....      100      gm. 

Potassium  bromide 1.5  gm. 

Water 500      c.c. 

For  use  take  equal  parts  of  No.  1  and  No.  2. 

The  hydroquinon  developer  may  be  made  in  one 
solution,  according  to  the  following  formula,  but 
should  be  made  fresh  for  each  day's  work: 

Hydroquinon 36  gm. 

Sodium  sulphite,  dry 90  gm. 

Potassium  carbonate,  dry 180  gm. 

Potassium  bromide 9  gm. 

Water 1 800  c.c. 

Hydroquinon  is  a  reducer  which  gives  great  con- 
trast in  pictures  and  since  this  is  a  very  desirable 
thing  in  radiographs  it  makes  a  good  developer  in 
X-ray  work.     Where  softer  negatives  with  greater 

4 


50  A  MANUAL  OF  X-RAY  TECHNIC 

detail  are  desired  metol  is  a  valuable  reducer.  Hydro- 
quinon  and  metol  may  be  used  together  according  to 
the  following  formula; 

No.   1.  Metol    1   gm. 

Hydroquinon .  4  gm. 

Sodium  sulphite 50  gm. 

Potassium  bromide,   10  per 

cent,  sol 4  c.c. 

Water 250  c.c. 

No.  2.  Sodium  carbonate 50  gm. 

Water 250  c.c. 

Mix  No.  1  and  No,  2  in  equal  parts. 

The  advantages  of  having  the  accelerator,  sodium 
carbonate,  in  a  separate  solution  are  that  the  developer 
keeps  better  and  that  development  is  better  under 
control.  If  the  plate  is  over-exposed  then  a  small 
amount  of  No.  2  should  be  added;  if  under-exposed, 
a  proportionately  larger  amount. 

After  the  negative  has  been  developed  it  is  neces- 
sary to  remove  the  silver  from  the  unexposed  parts 
of  the  film.  This  is  known  as  fixing,  and  is  effected 
by  placing  the  plate  in  a  solution  of  sodium  hypo- 
sulphite, made  according  to  the  following  formula: 

A 

Water    4000  c.c. 

Sodium  hyposulphite   1000  gm. 


RADIOGRAPHY  51 

B 

Water    . 1000  c.c. 

Sodium  sulphite,  dry 90  gm. 

Sulphuric  acid 15  c.c. 

Powdered  chrome  alum   60  gm. 

Mix  B  in  exactly  the  proportions  and  sequence 
given  above. 

Pour  B  into  A  while  stirring.  During  cold 
weather  one-half  of  B  is  sufficient  for  the  full  quantity 
of  A. 

TECHNIC  OF  RADIOGRAPHY. 

The  X-ray  plate  is  placed  in  a  black  envelope,  and 
the  latter  in  an  orange  envelope.  It  is  so  placed  that 
the  film  side  of  the  plate  is  next  to  the  smooth  side  of 
the  envelopes,  that  is,  the  side  opposite  the  flaps.  The 
film  side  is  recognized  by  its  dull  appearance  and  bj'^ 
the  fact  that  the  slightly  moistened  finger  sticks  to  it. 
Some  form  of  plate  holder  may  be  used  instead  of  the 
envelopes.  The  plate  is  placed  in  its  envelopes  or 
plate  holder  in  a  photographic  dark-room  illuminated 
only  by  a  good  ruby  light.  All  plates  kept  in  stock 
should  be  kept  in  a  lead-lined  box  in  a  cool,  dry  place, 
and  should  be  put  into  envelopes  or  plate  holder  only 
immediately  before  use. 

After  being  placed  in  its  envelopes  the  plate  is 
taken  to  the  X-ray  room  and  protected  from  the  X- 
ray  in  a  lead-lined  box  or  behind  a  lead  partition 


52  A  MANUAL  OF  X-RAY  TECHNIC 

while  the  tube  is  being  tried  and  regulated.  When 
the  tube  is  ready  the  plate  is  placed  under  the  patient 
with  its  centre  immediately  beneath  the  centre  of  the 
part  to  be  radiographed.  The  target  of  the  tube  is 
then  centred  over  the  centre  of  the  plate  at  a  distance 
of  18  to  25  inches  from  the  plate. 

No  definite  rules  can  be  given  for  the  time  of 
exposure,  since  it  differs  with  the  strength  of  the 
current,  the  condition  of  the  tube,  distance  of  the  tube 
from  the  plate,  thickness  of  the  part  to  be  radio- 
graphed, and  the  sensitiveness  of  the  plate.  Every 
radiographer  must  determine  the  time  of  exposure 
for  different  parts  of  the  body  on  his  particular 
apparatus.  By  recording  the  reading  of  the  milli- 
ammeter,  the  length  of  the  parallel  spark  gap,  the 
distance  of  tube  from  plate,  and  the  thickness  of  the 
part,  he  will  soon  be  able  to  estimate  very  closely  the 
exposure  time  in  each  particular  case.  In  general  it 
may  be  said  that  the  transformer  with  alternating 
current  supply  enables  one  to  do  the  most  rapid  work 
while  the  transformer  with  direct  current  is  next. 
Coil  apparatus  with  direct  current  comes  next  to  the 
transformer,  while  the  coil  with  alternating  current 
supply  requires  the  longest  exposures  of  all. 

At  the  present  time  excellent  intensifying  screens 
made  of  calcium  tungstate  are  to  be  had,  and  when 
properly  used  greatly  shorten  the  time  of  exposure. 


RADIOGRAPHY  53 

The  screen  should  be  brushed  oif  carefully  each  time 
before  using  and  should  be  placed  in  contact  with  the 
film  side  of  the  plate  against  which  it  must  be  snugly 
pressed  while  the  exposure  is  being  made.  The  ray 
must  pass  through  either  the  screen  or  the  plate  to 
reach  the  film.  The  latter  is  the  most  common 
method.  The  screen  enables  one  to  take  practically 
instantaneous  pictures  of  the  bismuth-filled  stomach 
and  colon  and  is  indispensable  for  such  work.  It  is 
not  possible  to  obtain  such  fine  detail  with  the  screen, 
however,  as  without  it. 

After  exposure  the  plate  is  taken  to  the  dark 
room,  removed  from  its  envelopes,  and  placed  in  the 
developing  solution.  It  should  be  slid  into  the  tray 
of  developer  and  the  solution  made  to  cover  the  entire 
plate  immediately  by  a  wave-like  motion.  It  is  im- 
portant that  the  developer  be  kept  at  a  temperature 
of  about  65°  to  68°  F.  All  air  bubbles  should  be  re- 
moved from  surface  of  the  plate  by  rocking  the  tray. 
Complete  development  is  judged  by  the  even  black 
appearance  of  the  back  of  the  plate  when  it  is  held 
up  to  the  ruby  light.  When  developed  the  plate  is 
washed  for  a  moment  in  running  water  and  placed 
in  the  fixer.  After  it  has  remained  in  the  fixer  for 
about  a  minute  the  light  may  be  turned  on.  The  plate 
is  fixed  when  all  the  dull  white  film  has  disappeared 
from  it, — a  fact  which  may  be  determined  by  looking 


54  A  IVIANUAL  OF  X-RAY  TECHNIC 

at  the  back  of  the  plate,  but  it  should  be  left  in  the 
solution  for  about  15  minutes  after  this  has  occurred. 
When  the  plate  is  fixed  it  should  be  washed  for  at 
least  an  hour  in  running  water. 

0\"ER-EXPOSED  Plates. — A  plate  on  which  the 
image  flashes  up  almost  immediately  upon  placing  it 
in  the  developer  is  usually  over-exposed,  and  if  de- 
veloped in  the  usual  way  would  be  so  dense  that  the 
picture  could  scarcely  be  seen.  It  may  be  taken  from 
the  developer  immediately  and  the  process  finished 
in  a  weaker  developer,  or  a  few  drops  of  10  per  cent. 
,  solution  of  potassium  bromide  may  be  added  to  re- 
strain the  development.  If  after  development  the 
plate  is  still  found  to  be  too  black  and  dense  it  may 
be  greatly  improved  by  treating  it  with  a  reducer. 
For  this  purpose  the  following  solution  may  be  used : 

Potassium  permanganate .5   gm. 

Sulphuric  acid 1       c.c. 

Water    1050      c.c. 

Before  treating  with  this  reducer  the  plate  should 
be  washed  but  does  not  require  to  be  entirely  free 
from  hypo.  Rock  the  dish  continually  while  the  plate 
is  in  the  reducer.  If  a  stain  is  left  by  the  permanga- 
nate it  may  be  removed  by  a  1  per  cent,  solution  of 
oxalic  acid. 

Potassium  cyanide  is  often  used  as  a  reducer 
according  to  the  following  formula: 


RADIOGRAPHY  55 

Potassium  cyanide 1      gm. 

Potassium  iodide   .5  gm. 

Mercuric  chloride .5  gm. 

Water    300      c.c. 

The  plate  must  be  well  washed  to  remove  the 
poisonous  chemicals  in  the  above  formula. 

Under-exposed  Plates. — Plates  that  have  had 
insufficient  exposure  will  need  to  be  developed  for  a 
long  time  in  a  strong  developer.  Leaving  them  in  too 
long,  however,  will  often  fog  them.  Under-exposed 
plates  may  be  much  improved  by  treating  them  with 
an  intensifying  solution  such  as  the  following: 

Mercuric  chloride 11   gm. 

Potassium  bromide 6  gm. 

Water    210  c.c. 

Leave  the  plate  in  this  solution  until  it  looks  white, 
then  wash  it  in  running  water  for  about  one-half  hour. 
The  plate  is  then  placed  in 

Sodium  sulphite    45  gm. 

Water    180  c.c. 

until  it  has  turned  black,  and  is  then  thoroughly 
washed. 

Of  course  the  ideal  is  to  give  the  correct  exposure 
and  to  develop  to  the  proper  density,  but  this  is  not 
always  attained,  and  many  otherwise  valueless  plates 
may  be  saved  by  reduction  or  intensification. 

Practice  is  the  only  way  to  become  proficient  in 
taking  and  developing  radiograms. 


CHAPTER  VII. 

Fluoroscopy.    Stereoscopic  Radiography. 
Localization  of  Foreign  Bodies. 

fluoroscopy. 

The  fluoroscopic  screen  is  made  of  platinobarium 
cyanide  crystals  which  fluoresce  when  the  X-ray 
falls  upon  them.  This  screen  may  be  fitted  into 
the  end  of  a  light-proof  box  into  which  the  observer 
looks,  or  built  into  other  forms  of  apparatus.  When 
a  part  of  the  body  is  held  between  the  screen  and  the 
X-ray  tube  the  rays  pass  with  varying  degrees  of 
penetration.  Around  the  part  where  there  is  no  ob- 
struction, they  cause  the  screen  to  fluoresce  very  brill- 
iantly; under  the  soft  parts  the  fluorescence  is  less 
brilliant ;  and  if  the  degree  of  penetration  is  too  great 
there  is  no  fluorescence  at  all  beneath  the  bones,  and 
they  appear  black. 

The  long  exposures  necessary  for  fluoroscopic 
work  have  made  it  a  very  dangerous  method  to  the 
operator,  a  fact  all-too-well  proven  by  the  loss  of 
limbs  and  even  of  lives  of  radiographers.  Apparatus 
is  now  built,  however,  so  that  fluoroscopic  work  may 
be  done  while  the  operator  remains  well  protected 
even  from  secondary  radiations. 

56 


FLUOROSCOPY  57 

It  is  essential  for  good  fluoroscopic  work  that  the 
voltage  be  as  high  as  possible,  but  only  a  few  milli- 
amperes  of  current  are  necessary.  The  static  ma- 
chine is  therefore  ideal  for  this  purpose.  Satisfactory 
fluoroscopic  work  may  be  done,  however,  with  either 
coil  or  transformer  if  they  are  equipped  with  some 
arrangement  for  delivering  a  very  small  current  to 
the  tube  without  lessening  the  voltage.  Different 
manufacturers  have  accomplished  this  in  different 
ways.  Some  makes  of  apparatus  are  so  arranged  that 
a  variable  number  of  windings  of  the  primary  may  be 
used,  others  depend  upon  a  choke-coil  in  which  in- 
ductance reduces  the  current  strength  with  practically 
no  change  in  the  voltage.  Another  arrangement, 
which  has  proven  very  satisfactory  in  operation,  is  the 
invention  of  Dr.  Harry  Waite  of  New  York.  It  is 
essentially  a  revolving  disc  fixed  upon  the  same  shaft 
as  the  motor  and  the  rectifying  switches.  A  metal 
plate  forms  a  quarter  of  the  circle  of  this  disc  which 
is  mounted  so  that  three  carbon  brushes  connected 
in  the  primary  circuit  press  against  it.  The  leads 
from  these  three  brushes  pass  through  a  rocking 
switch  and  the  connections  are  so  made  that  when  the 
switch  is  open  only  fifteen  of  the  sixty  cycles  of  the 
alternating  current  are  transmitted;  when  the  switch 
is  closed  on  one  side  thirty  cycles  of  the  current  will 
pass,  while  if  it  is  closed  on  the  other  side  the  current 


58  A  MANUAL  OF  X-RAY  TECHNIC 

is  short-circuited  through  the  switch  and  the  full 
sixty  cycles  are  transmitted  to  the  tube.  Excellent 
fluoroscopic  work  may  be  done  with  both  the  fifteen- 
and  thirty-cycle  current  with  very  little  wear  on  the 
tube. 

The  best  field  for  fluoroscopy  is  the  chest,  in  which 
the  contrast  between  the  different  parts  is  great 
enough  to  render  the  shadows  very  distinct.  The 
presence  of  cardiac  hypertrophy  or  aneurism  of  the 
aorta  is  readily  made  out.  Limitations  in  the  ex- 
cursion of  the  diaphragm  may  be  seen  and  the  extent 
of  pleuritic  effusion  determined.  Gross  lesions  of  the 
lungs  are  rendered  visible,  but  for  the  finer  lesions 
fluoroscopy  is  much  less  valuable  than  radiography. 

Fluoroscopy  has  also  been  found  of  considerable 
help  in  studying  the  movements  of  the  stomach  filled 
with  a  bismuth  meal,  and  of  the  colon  while  giving  a 
bismuth  enema. 

The  operator  should  never  lose  sight  of  the  danger 
of  exposing  himself  to  the  X-ray,  and  should  do 
fluoroscopy  only  under  the  most  favorable  conditions. 
The  room  should  be  completely  darkened  and  the 
operator  should  remain  in  the  dark  at  least  three 
minutes  before  the  ray  is  turned  on.  It  is  only  by 
observing  these  two  points  that  satisfactory  fluoro- 
scopic work  can  be  done.  The  smallest  current  that 
will  give  distinct  shadows  should  be  employed  and  the 


STEREOSCOPIC  RADIOGRAPHY  59 

opening  in  the  diaphragm  should  be  reduced  to  the 
smallest  size  practicable  for  the  work  in  hand.  For 
the  safety  of  the  patient  it  is  important  that  the 
examination  be  made  in  as  short  a  time  as  possible. 

With  the  proper  apparatus,  and  observance  of 
the  necessary  precautions,  there  is  no  doubt  that 
fluoroscopy  will  increase  in  value. 

STEREOSCOPIC  RADIOGRAPHY. 

Radiograms  are  necessarily  perfectly  flat  pictures, 
— that  is,  they  give  no  perspective.  It  is  often  of  the 
greatest  advantage  to  be  able  to  tell  which  parts  in 
the  picture  project  towards,  and  which  parts  away 
from,  the  observer.  For  this  purpose  stereoscopic 
radiograms  are  made.  This  is  done  by  taking  two 
pictures  of  the  part,  the  plate  for  the  second  one  being 
placed  in  exactly  the  same  position  as  the  first,  the 
tube  having  been  displaced  laterally  a  short  distance. 
Both  pictures  must  be  taken  without  any  movement 
on  the  part  of  the  patient.  This  procedure  gives  two 
pictures  of  the  part,  taken  from  slightly  difl*erent 
view-points,  which  may  be  placed  side  by  side  and 
fused  into  one  image  by  some  form  of  reflecting  or 
refracting  stereoscope.  The  observer  thus  gets  a 
sense  of  perspective,  or  depth,  in  the  picture  and  sees 
all  the  parts  in  their  proper  relations. 


60  A  MANUAL  OF  X-RAY  TECHNIC 

The  technic  of  making  stereoscopic  radiograms  is 
not  difficult.  It  is  necessary  only  to  have  some  form 
of  plate-changing  device  so  that  the  second  plate  may 
be  substituted  for  the  first  without  any  movement  of 
the  patient,  and  such  construction  of  the  tube-holder 
as  will  provide  for  readily  shifting  the  position  of  the 
tube.  Most  tables  and  tube-holders  are  now  con- 
structed to  meet  all  the  requirements  of  stereoscopic 
work. 

The  procedure  in  making  stereoscopic  radiograms 
is  as  follows :  The  part  to  be  radiographed  is  placed 
firmly  upon  the  plate-holder  so  that  no  movement 
will  take  place.  A  plate  is  placed  in  the  plate-holder 
and  the  first  exposure  made.  The  plate  is  then  re- 
moved and  another  placed  in  the  holder  in  exactly  the 
same  position  as  the  first  one.  The  tube  is  then 
shifted  to  the  right  or  left  of  its  first  position  for  a 
distance  of  about  three  inches,  corresponding  to  the 
distance  between  the  pupils  of  the  eyes,  and  a  second 
exposure  made.  When  developed  these  two  plates 
are  placed  side  by  side,  and  viewed  with  a  stereoscope. 
Positives  can  then  be  made  on  one  small  plate  and  the 
pictures  viewed  conveniently  through  the  common 
hand  stereoscope. 

Stereoscopic  radiograms  are  invaluable  in 
fractures  and  dislocations,  the  relation  to  each  other 
of  the  fragments  or  displaced  articular  surfaces  being 


LOCALIZATION  OF  FOREIGN  BODIES  61 

shown  accurately.  The  position  of  foreign  bodies  in 
relation  to  surrounding  parts  can  be  seen  very 
clearly.  The  value  of  radiography  in  the  diagnosis 
of  intrathoracic  disease  has  been  increased  greatly 
by  stereoscopic  work.  Stereoscopic  radiography  has 
also  been  found  of  definite  value  in  the  study  of  the 
bismuth-filled  colon.  Study  of  the  nasal  accessory 
sinuses  is  also  rendered  much  more  intelligent  if 
stereoscopic  radiograms  are  taken. 

No  radiographer  who  has  once  recognized  the 
immense  improvement  of  stereoradiographs  over  the 
simple  flat  picture,  especially  in  fractures,  disloca- 
tions, and  intrathoracic  lesions,  and  in  the  study  of 
the  colon,  will  ever  be  content  to  rest  a  diagnosis  upon 
the  evidence  furnished  by  the  simple  radiogram. 

THE  LOCALIZATION  OF  FOREIGN  BODIES. 

The  image  of  foreign  bodies  in  the  tissues  may  be 
seen  on  the  fluorescent  screen,  and  also  in  simple 
radiograms,  but  it  is  often  difficult  to  estimate  their 
distance  from  the  surface. 

Many  diiferent  methods  have  been  used  for  the 
accurate  localization  of  foreign  bodies. 

The  Stereoscopic  method  has  already  been  men- 
tioned and  is  of  undoubted  value  unless  it  is  necessary 
to  make  an  absolutely  accurate  localization. 


62  A  IMANUAL  OF  X-RAY  TECHNIC 

The  Triangulation  method  necessitates  such  com- 
plicated mathematical  calculation  that  it  is  very  little 
used. 

The  Mackenzie-Davidson  method  is  probably  the 
one  most  commonly  employed  and  has  been  found 
perfectly  satisfactory  by  the  author.  Briefly,  it  con- 
sists of  making  two  exposures  upon  the  same  plate 
without  any  movement  of  the  patient  or  the  plate,  the 
tube  being  shifted  laterally  a  kno^Mi  distance  for  the 
second  exposure.  To  carry  out  this  method  the  plate 
is  placed  on  the  table  beneath  two  crossed  wires.  One 
of  these  wires  must  be  parallel  to  the  horizontal  bar 
carrying  the  tube,  so  that  when  the  tube  is  displaced 
the  focus  point  on  the  target  will  always  be  per- 
pendicularly above  a  point  in  the  w^ire.  The  focus 
point  of  the  target  is  accurately  centred  perpendicu- 
larly above  the  point  of  intersection  of  the  cross-wires. 
The  tube  is  now  displaced  a  known  distance,  two 
inches  for  instance,  from  the  centre.  The  part  to  be 
radiographed  is  placed  firmly  upon  the  table.  It  is 
necessarj^  to  have  the  position  of  the  cross-wires 
marked  upon  the  patient's  body,  and  this  may  readily 
be  done  by  inking  the  wires,  or  when  the  patient  arises 
by  rendering  the  red  marks  left  by  the  wires  more 
permanent  by  the  marks  of  an  indelible  pencil.  It  is 
also  well  to  place  a  small  lead  marker  on  one  corner 
of  the  plate  and  to  mark  its  position  on  the  patient's 


LOCALIZATION  OF  FOREIGN  BODIES  63 

body.  The  first  exposure  is  now  made,  and  without 
movement  on  the  part  of  the  patient,  or  movement 
of  the  plate,  the  tube  is  shifted  two  inches  to  the  other 
side  of  the  centre  and  the  second  exposure  made.  The 
plate  is  then  developed  and  shows  the  images  of  the 
cross  wires  dividing  the  plate  into  quadrants,  two 
images  of  the  foreign  body,  and  the  image  of  the  lead 
marker  which  enables  one  to  select  the  corresponding 
quadrants  on  plate  and  patient.  The  plate  is  placed 
on  a  table  beneath  a  horizontal  bar  from  which  two 
threads  are  hanging.  The  bar  is  the  same  distance 
above  the  plate  as  the  focus  point  on  the  target  of  the 
tube  was  in  taking  the  pictures.  The  threads  are 
fixed  on  the  bar  two  inches  each  side  of  a  point  which 
is  perpendicularly  above  the  point  of  intersection  of 
the  image  of  the  cross-wires  on  the  plate,  thus  repre- 
senting the  target  of  the  tube  in  its  two  different 
positions.  Not  only  must  the  intersecting  point  on 
the  plate  be  perpendicularly  beneath  the  selected 
middle  point  on  the  bar  but  one  of  the  cross-wires 
must  be  parallel  to  the  bar. 

The  end  of  one  of  the  threads  is  now  placed  upon 
a  point  in  one  image  of  the  foreign  body,  and  the  end 
of  the  other  thread  upon  the  corresponding  point  in 
the  other  image.  The  point  where  the  threads  cross 
obviously  represents  the  position  of  the  foreign  body 
in  relation  to  the  plate.     A  perpendicular  can  be 


64  A  MANUAL  OF  X-RAY  TECHNIC 

dropped  from  this  point  to  the  plate  and  a  mark  made 
on  the  plate.  If  the  foreign  body  is  large,  like  a 
bullet  for  instance,  each  end  of  it  can  be  localized  in 
this  manner. 

The  distance  of  the  mark  on  the  plate  from  the 
two  cross-wires  can  now  be  measured. 

The  perpendicular  distance  of  the  point  of  inter- 
section of  the  threads  from  the  plate  represents  the 
distance  of  the  foreign  body  beneath  the  skin  which 
rests  upon  the  plate.  The  marks  of  the  wires  being 
left  upon  the  patient's  skin  it  is  only  necessary  to 
measure  the  distances  found  above  from  each  wire. 
The  point  of  intersection  of  lines  representing  these 
two  measurements  gives  the  point  on  the  patient's 
body  below  which  will  be  found  the  foreign  body,  at 
the  exact  distance  ascertained  above. 

This  method  is  rapid  and  accurate  and  requires 
no  complicated  mathematical  calculations  in  its  appli- 
cation. 

For  the  localization  of  foreign  bodies  in  the  eye  it 
is  necessary  to  have  some  special  form  of  apparatus. 
The  localizer  devised  by  Dr.  Sweet,  of  Philadelphia, 
is  the  one  used  by  the  author,  and  has  been  found 
perfectly  satisfactory.  Detailed  description  of  the 
method  of  using  this  apparatus  can  be  obtained  from 
the  manufacturer  and  will  not  be  included  here. 


CHAPTER  VIII. 

Diseases  and  Injuries  of  Bones  and  Joints. 

There  seems  to  be  little  necessity  for  insisting 
upon  the  importance  of  X-ray  examination  of  bone 
and  joint  lesions,  for  this  is  the  field  in  which  radio- 
graphy has  proven  of  the  greatest  value. 

It  should  be  an  invariable  rule  to  secure  radio- 
grams, not  only  in  cases  of  undoubted  fracture  or  dis- 
location, but  in  every  case  of  injury  to  the  bones.  This 
is  especially  important  when  the  injury  is  near  a 
joint.  The  necessity  for  this  is  demonstrated  by  the 
great  number  of  cases  in  which  no  clinical  diagnosis 
could  be  made  other  than  contusion  or  sprain,  and  in 
which  the  radiogram  revealed  a  fracture  or  disloca- 
tion. Radiograms  are  especially  valuable  in  bone  and 
joint  injuries  to  establish  the  presence  or  absence  of 
a  complicating  lesion,  such,  for  instance,  as  a  fracture 
of  the  greater  tuberosity  or  head  of  the  humerus  in 
shoulder- joint  dislocations,  or  dislocations  of  the 
carpal  or  tarsal  bones  in  injuries  about  the  wrist  or 
ankle. 

In  examining  bones  either  for  injuries  or  diseases 
it  is  always  well,  where  practicable,  to  make  radio- 
grams from  two  different  angles.    The  target  of  the 

5  65 


66  A  MANUAL  OF  X-RAY  TECHNIC 

X-ray  tube  should  be  centred  directly  over  the  lesion 
to  avoid  the  distortion  which  occurs  if  the  picture  is 
taken  obliquely  and  which  may  give  an  entirely  erro- 
neous impression  of  the  amount  of  overriding  or 
separation  of  the  fragments  in  fractures. 

Stereoscopic  radiograms  are  invaluable  in  deter- 
mining the  correct  relation  of  the  fragments  in 
fractures  and  of  the  articular  surfaces  in  dislocations. 

No  special  instructions  need  be  given  for  radio- 
graphing the  different  joints  of  the  body,  but  a  few 
practical  points  may  be  mentioned. 

The  spinal  column  in  the  lumbar  and  lowermost 
dorsal  regions  should  be  taken  anteroposteriorly. 
The  cervical  region  may  be  taken  both  anteroposte- 
riorly and  laterally.  The  thoracic  spine  shows  very 
poorly  in  radiograms  taken  in  the  anteroposterior 
direction,  and  only  fairly  well  in  the  lateral.  It  is 
possible,  however,  to  secure  good  radiograms  of  it 
if  the  patient  is  turned  partly  on  the  left  side  so  that 
the  ray  enters  at  a  point  about  two  inches  outside  of 
the  right  nipple  and  passes  backward  and  to  the  left 
through  the  spine.  This  prevents  superimposing  the 
shadows  of  the  sternum  and  the  great  vessels  upon 
that  of  the  spine. 

The  shoulder  should  be  radiographed  with  the 
target  centred  over  the  glenoid  cavity,  the  patient 
being  in  either  the  prone  or  supine  position.    Stereo- 


BONES  AND  JOINTS  67 

scopic  radiograms  should  always  be  made  in  cases  of 
fracture  or  dislocation  of  the  shoulder. 

The  elbow,  wrist,  knee,  and  ankle  should  be  radio- 
graphed both  anteroposteriorly  and  laterally.  The 
side  with  the  lesion  should  be  placed  nearest  to  the 
plate. 

Radiograms  of  the  hip  are  made  with  the  target 
directly  over  the  centre  of  the  acetabulum,  the  patient 
usually  lying  upon  the  back.  In  interpreting  radio- 
grams of  the  hip  it  is  important  to  remember  that  the 
arch  formed  by  the  under  surface  of  the  neck  of  the 
femur  and  the  upper  border  of  the  obturator  foramen 
normally  make  an  unbroken  curve.  Good  radiograms 
of  the  hip  should  show  the  posterior  border  of  the 
acetabulum  through  the  head  of  the  femur. 

DISEASES  OF  THE  BONES  AND  JOINTS. 

Periostitis  and  ostitis,  whether  of  traumatic  ot 
infectious  origin,  are  usually  associated.  Early  in  the 
disease  when  there  is  only  periosteal  involvement  the 
only  thing  to  be  seen  in  the  radiogram  is  a  bulging 
in  the  contour  of  the  bone  at  the  site  of  the  lesion. 
Later  a  distinct  shadow  is  produced  by  the  exudate 
thrown  out,  and  later  still  the  dense  shadows  due  to 
sclerotic  changes  are  seen. 

Osteomyelitis  shows  the  exudative  and  sclerotic 
changes  of  periostitis  and  ostitis,  but  in  addition, 


68  A  MANUAL  OF  X-RAY  TECHNIC 

changes  due  to  bone  destruction  are  evident.  Well- 
marked  abscesses,  and  cavities  due  to  necrosis,  are 
present.  In  older  cases  sequestra  are  seen.  The 
course  of  sinuses  through  the  bone  and  soft  tissues 
may  be  marked  out  by  injecting  bismuth  paste.  To 
show  the  exact  course  and  relations  of  the  sinus 
stereoscopic  radiograms  should  be  made. 

Tuberculosis. — The  distinguishing  characteristic 
of  tuberculosis  of  bone  is  the  absence  of  lime  salts, 
causing  the  shadow  of  the  bone  to  appear  faint  and 
indistinct.  It  usually  attacks  the  epiphyses  and 
seldom  involves  the  periosteum,  the  contrary  being 
the  case  with  syphilis. 

Syphilis. — Bone  destruction  due  to  syphilis  pre- 
sents an  irregular  moth-eaten  appearance  quite  char- 
acteristic of  this  disease.  The  periosteum  is  nearly 
always  involved  and  sclerotic  changes  which  produce 
dense  shadows  in  the  radiogram  are  always  present. 

Syphilis  is  distinguished  from  tuberculosis  by 
these  dense  black  shadows  which  are  in  distinct  con- 
trast to  the  faint  shadows  of  the  latter  disease. 

Osteomyelitis  of  non-syphilitic  origin  does  not 
show  such  extensive  periosteal  involvement  nor  does 
it  present  the  irregular  moth-eaten  appearance  of 
syphilitic  bone  disease. 

The  shadow  of  osteosarcoma  is  considerably  less 
dense  than  that  of  gumma.    The  most  important  dis- 


BONES  AND  JOINTS  69 

tinguishing  point  between  these  two  is  that  gumma 
remains  confined  to  the  bone  and  periosteum  while 
sarcoma  invades  the  soft  tissues. 

Arthritis  Deformans. — The  theory  of  the  causa- 
tion of  arthritis  deformans,  which  seems  to  be  gaining 
rapidly  in  acceptance,  is  that  the  disease  is  of  infec- 
tious origin,  and  that  it  is  usually  due  to  infection 
from  some  pre-existing  focus  in  the  body.  Accord- 
ing to  this  theory  the  disease  may  be  due  to  the 
streptococcus,  staphylococcus,  gonococcus,  or  to  any 
other  organisms  which  may  invade  the  joint,  the 
pathological  changes  differing  little  with  the  various 
organisms. 

This  theory  has  now  a  large  amount  of  clinical, 
and  some  experimental,  evidence  to  support  it. 

The  radiographic  appearances  vary  greatly  from 
almost  no  change  whatever  to  extensive  hypertrophic 
alterations.  In  the  first  class  of  cases  there  may  be 
considerable  swelling  about  the  joint  and  the  disease 
may  run  a  chronic  course,  but  the  radiogram  shows 
no  change  in  the  bones  except  a  slightly  decreased 
density. 

Other  cases  have  the  characteristics  of  a  productive 
osteitis.  There  is  increased  density  in  the  ends  of  the 
bones,  some  exudate  may  be  present,  and  there  may  be 
"  lipping  "  about  the  joint.  Any  degree  of  these 
changes  may  be  present  up  to  the  condition  in  which 


70  A  MANUAL  OF  X-RAY  TECHNIC 

there  is  extensive  bone  formation  about  the  joint,  with 
great  limitation  of  motion. 

Spondylitis  deformans,  unless  arrested,  passes 
through  all  of  the  above  stages,  from  that  in  which 
there  is  only  slight  irregularity  along  the  articular 
margins  to  that  of  complete  welding  of  the  vertebrae 
by  bridges  of  solid  bone. 

Exostoses  are  readily  recognized  in  radiograms. 
They  present  themselves  as  irregular  masses  of 
osseous  tissue  springing  directly  from  the  bone  and 
having  a  more  compact  appearance  than  normal  bone. 
Exostoses  give  a  much  heavier  shadow  than  osteo- 
sarcomata,  and  are  more  irregular  in  contour. 

Enchondromata  are  most  often  found  in  the 
bones  of  the  fingers  and  toes,  but  may  occur  in  the 
long  bones.  They  are  often  multiple,  an  important 
point  in  differentiating  from  osteosarcoma.  These 
enchondromata  have  a  transparent  appearance  but 
usually  have  small  islands  of  osseous  tissue  or 
trabeculse  traversing  them.  They  are  distinguished 
from  sarcoma  by  the  fact  that  they  are  often  multiple, 
have  areas  of  osseous  tissue,  and  that  they  do  not 
invade  the  soft  parts. 

Osteosarcoma  may  be  of  periosteal  or  of  myelog- 
enous origin.  These  tumors  have  a  pale,  homogeneous 
appearance  and  regular,  rounded  margin.  There  is 
almost  complete  disappearance  of  the  bony  tissue, 


BONES  AND  JOINTS  71 

leaving  in  some  cases  a  mere  shell  at  the  periphery. 
In  the  slower  growing  types  there  may  be  trabeculae 
distributed  irregularly  through  the  tumor. 

Bone-cysts  and  osteosarcomata  are  the  two  most 
difficult  lesions  to  differentiate  radiographically.  Be- 
nign bone-cysts  present  a  clean-cut  translucent 
appearance,  much  like  the  early  appearance  of  a  slow 
growing  sarcoma.  The  latter,  however,  is  usually 
single  while  benign  cysts  are  more  often  multiple. 
The  sarcoma  soon  increases  in  size  and  encroaches 
upon  the  soft  tissues  and  can  then  be  differentiated 
from  bone-cyst. 


CHAPTER  IX. 
X-Ray  Examination  of  the  Head. 

Fractures. — Lateral  radiograms  of  the  head 
show  fractures  of  the  vault  very  well,  but  it  is  only 
rarely  that  fractures  of  the  base  can  be  shown. 

Fractures  of  the  lower  jaw  can  be  shown  quite 
plainly  if  care  is  taken  to  have  the  head  in  the  best 
position  and  the  rays  passing  at  the  correct  angle. 
Fig.  21  illustrates  the  method  used  by  the  author. 
The  fractured  side  should  be  nearest  to  the  plate.  The 
wedge-shaped  block  of  wood  shown  in  this  illustration 
is  useful  for  most  head  pictures  and  should  be  a  part 
of  the  equipment. 

New  (Growths. — Tumors  of  the  bones  of  the 
skull  or  in  the  sinuses  or  orbit  can  usually  be  shown 
in  a  radiogram,  but  it  is  very  seldom  that  much  in- 
formation can  be  gained  concerning  intracranial 
tumors.  Tumor  involving  the  pituitary  body  may 
cause  absorption  of  the  sella  turcica  and  surrounding 
bony  tissue  and  its  presence  diagnosed  because  of  this. 

The  Accessory  Sinuses. — Much  valuable  in- 
formation may  be  gained  by  radiography  of  the  nasal 
accessory  sinuses.  The  correct  relation  of  tube  and 
patient  is  of  the  utmost  importance  in  radiography 
of  the  sinuses. 

72 


X-RAY  EXAMINATION  OF  THE  HEAD  73 

The  Frontal  Sinuses. — The  position  of  patient 
and  tube  is  shown  in  Fig.  22.  The  patient's  head  is 
placed  on  the  wedge-shaped  block  with  forehead  and 
tip  of  nose  touching  the  plate.  The  target  is  centred 
over  a  point  about  midway  between  the  occipital 
protuberance  and  the  vertex.  If  the  ray  passes  at  a 
lower  plane  shadows  of  the  heavy  bones  at  the  base  of 
the  skull  will  blot  out  those  of  the  sinuses,  and  if  a 
higher  point  is  selected  the  shadows  of  the  sinuses  will 
be  greatly  distorted.  Thickening  of  the  mucous  mem- 
brane causes  a  blurring  of  the  shadow  on  the  affected 
side,  and  the  presence  of  pus,  tumor,  or  granulation 
tissue  renders  the  sinus  so  opaque  to  the  ray  that  a 
dense  white  shadow  is  thrown.  In  the  presence  of 
symptoms  of  inflammation  of  the  accessory  sinuses 
radiographs  are  of  immense  help  in  locating  the  sinus 
involved.  The  presence  or  absence  of  one  or  both 
frontal  sinuses  may  be  established  by  good  radio- 
grams. 

The  MAXILLARY  ANTRA  may  be  radiographed  with 
the  tube  in  the  same  position  as  for  the  frontal  sinuses, 
or  with  the  ray  directed  at  a  point  well  below  the  base 
of  the  skull.  Difference  in  the  opacity  of  the  shadows 
on  the  two  sides  is  the  point  of  importance  in  making 
a  diagnosis. 

The  sphenoidal  sinuses  can  be  shown  in  radio- 
grams, but  it  requires  considerable  skill  in  technic  and 


74  A  MANUAL  OF  X-RAY  TECHNIC 

experience  in  interpretation  to  be  able  to  draw  con- 
clusions as  to  their  condition.  To  study  these  sinuses 
Pfahler  makes  six  radiograms,  two  postero-anterior, 
two  lateral  (stereoscopically),  and  two  oblique/ 

Dental  Radiography. — There  are  two  methods 
of  making  radiograms  of  the  teeth,  the  intra-oral  and 
the  extra-oral  method. 

In  the  intra-oral  method  a  small  photographic 
film  wrapped  in  black  paper  is  placed  inside  the  mouth, 
as  nearly  as  possible  against  the  teeth  that  are  under 
investigation.  In  the  extra-oral  method  the  picture 
is  taken  upon  an  X-ray  plate  placed  beneath  the 
patient's  head  (Fig.  21). 

In  both  methods  the  important  point  is  to  have 
the  correct  angle  of  incidence  of  the  X-rays  upon  the 
film  or  plate.  This  is  especially  true  of  the  intra-oral 
method.  It  is  readily  seen  that  in  radiographing  the 
teeth  of  the  upper  jaw  the  film  cannot  be  placed 
parallel  to  the  teeth.  Its  position  depends  upon  the 
slant  of  the  roof  of  the  mouth.  If  the  picture  is  made 
with  the  direction  of  the  rays  at  right  angles  to  the 
teeth  they  will  appear  elongated  and  distorted,  while 
if  the  angle  is  too  small  the  shadow  of  the  teeth  will  be 
foreshortened.  Fig.  23  illustrates  the  proper  position 
for  the  majority  of  cases  for  radiography  of  the 
front  teeth  of  the  upper  jaw. 

*  The  Amer.  Quarterly  of  Rontgenology,  November,  1912. 


Fig.  21. — Position  for  lateral  radiography  of  head. 


Fig.  22. — Radiography  of  frontal  sinuses. 


X-RAY  EXAMINATION  OF  THE  HEAD  75 

The  intra-oral  method  is  the  best  for  all  cases  in 
which  it  is  desired  to  secure  detail  about  the  teeth,  but 
for  fractures  of  either  jaw,  and  in  cases  where  it  is 
necessary  to  show  the  relations  over  a  wider  area  than 
can  be  covered  by  a  film  the  extra-oral  method  is 
applicable.  Fig.  21  illustrates  the  proper  relation  of 
the  patient  to  the  plate  and  tube  in  taking  these 
pictures. 

Good  radiograms  of  the  teeth  and  jaws  give  much 
valuable  information  in  various  abnormal  conditions. 
Among  these  may  be  mentioned  pyorrhoea  alveolaris, 
localized  alveolar  abscess,  the  presence  or  absence  and 
the  position  of  unerupted  teeth,  the  condition  of  root 
fillings  and  pivot  teeth,  and  the  presence  of  a  foreign 
body  such  as  a  broken  drill. 


CHAPTER  X. 

The  Thorax. 

Fluoroscopy  is  of  greater  value  in  examination 
of  the  thorax  than  of  any  other  part  of  the  body  be- 
cause of  the  gi'eat  contrast  produced  in  the  shadows 
by  the  air-filled  lungs. 

Some  radiologists  use  fluoroscopy  alone  for 
examination  of  the  thoracic  organs,  while  others  rely 
almost  entirely  upon  radiography. 

It  seems  the  best  practice  to  make  use  of  fluoros- 
copy to  determine  the  mobility  of  ribs  and  dia- 
phragm, the  presence  of  expansile  pulsation  in  sus- 
pected aneurism,  the  presence  of  such  gross  lesions  as 
pleural  effusion  or  pneumothorax,  and  in  a  general 
way  the  aeration  of  different  parts  of  the  lung. 

The  fine  details  of  lung  structure,  however,  can  be 
studied  only  in  radiograms,  so  that  it  is  necessary  to 
make  them  both  for  purposes  of  diagnosis  and  in 
order  to  have  a  permanent  record  of  the  case. 

The  technic  of  radiography  of  the  thorax  is  not 
difficult,  but  considerable  care  and  experience  are 
necessary  to  secure  radiograms  which  give  th^  great- 
est possible  detail. 

Stereoscopic  radiograms  are  of  immense  value  in 
diagnosing  intrathoracic  conditions,  so  much  so  that 

76 


THE  THORAX  77 

the  author  no  longer  makes  single  radiograms  of  the 
chest.  In  the  stereogram  every  structure  appears  in 
its  true  relation  to  other  structures,  making  it  possible 
to  avoid  those  mistakes  in  interpretation  unavoidably 
caused  by  the  superimposed  shadows  of  the  flat 
picture. 

With  the  patient  in  either  the  erect  or  prone  posi- 
tion the  target  of  the  tube  is  centred  over  the  spinal 
column  at  the  lower  level  of  the  scapulse,  the  distance 
from  the  plate  being  at  least  twenty-five  inches.  The 
patient  inhales  deeply  and  the  first  exposure  is  made. 
While  he  holds  his  breath  the  tube  is  sliifted  three 
inches  towards  his  feet,  a  second  plate  substituted  for 
the  first,  and  the  second  exposure  made.  The  entire 
time  for  this  complete  operation  ought  not  to  be  more 
than  ten  or  twelve  seconds,  since  some  patients  can- 
not hold  the  breath  for  a  longer  time. 

For  adults  the  plates  should  be  14  x  17  inches. 
Plates  of  such  large  size  make  the  expense  of  stereo- 
radiography a  material  consideration,  but  the  added 
accuracy  in  diagnosis  justifies  the  use  of  this  method. 

Screen  Examination. — In  studying  the  chest 
upon  the  fluorescent  screen  one  of  the  first  things  to 
be  observed  is  the  movement  of  the  diaphragm.  Di- 
minished excursion  of  the  diaphragm  is  often  found 
in  diseases  of  the  lungs  and  pleura  (Williams'  sign). 
This  sign  if  present  is  of  marked  value  in  directing 


78  A  MANUAL  OF  X-RAY  TECHNIC 

attention  to  early  pulmonary  tuberculosis,  but  it  is  too 
often  absent  even  in  advanced  eases  to  be  of  great 
value. 

The  Heart. — The  size  of  the  heart  may  be  made 
out  roughly  on  the  screen  or  plate,  and  quite  accu- 
rately with  the  orthodiagraph.  In  a  short  work  of  this 
kind  space  cannot  be  given  for  description  of  the  latter 
method.  Separation  of  the  tube  to  a  distance  of  five 
feet  or  more  from  the  plate  lessens  the  exaggeration 
so  that  it  is  almost  negligible  and  one  can  arrive  at  a 
fairly  accurate  judgment  of  the  size  of  the  heart  with- 
out orthodiagraphy. 

An  important  feature  to  note  is  the  angle  formed 
by  the  right  ventricle  with  the  diaphragm,  the  cardio- 
hepatic  angle,  which  is  obliterated  in  pericarditis  with 
effusion  but  not  in  cardiac  enlargements. 

Thoracic  Aneurism. — The  best  position  for 
screen  examination  is  that  with  the  ray  passing  from 
behind  and  the  patient  turned  obliquely  with  the  right 
anterior  part  of  the  chest  pressing  against  the  screen. 

Care  should  be  taken  not  to  diagnose  as  aneurism 
the  slight  bulging  of  the  aortic  arch  to  the  left  which 
often  occurs  in  normal  subjects. 

The  diagnosis  of  thoracic  aneurism  is  based  upon 
the  appearance  of  a  large,  smoothly  rounded  shadow 
in  which  expansile  pulsation  can  often  be  detected. 

Tumors  of  the  posterior  mediastinum  are  more 


THE  THORAX  79 

likely  to  be  irregular  in  outline  rather  than  smooth 
like  aneurism,  and  one  may  be  able  to  distinguish  the 
shadow  of  the  normal  aorta  separate  from  the  tumor. 

Pneumothorax. — This  condition  is  readily  diag- 
nosed either  by  screen  examination  or  by  radiography. 
The  space  filled  by  the  air  offers  but  little  resistance 
to  the  passage  of  the  ray,  so  that  it  appears  very  bright 
on  the  screen  and  perfectly  black  on  radiograms. 
Another  important  point,  and  one  which  distinguishes 
pneumothorax  from  emphysema,  is  the  absence  of  the 
lung  markings  over  the  area  occupied  by  the  air. 

Pleurisy. — Acute  pleurisy  without  effusion  gives 
no  radiologic  evidence  except  limitation  of  movement 
of  ribs  and  diaphragm.  Pleurisy  with  effusion 
causes  a  dense  shadow,  which  is  first  noted  in  the 
angle  between  the  diaphragm  and  ribs.  The  fact  that 
the  density  of  the  shadow  is  unaffected  by  respiration 
distinguishes  it  from  pulmonary  consolidations.  If 
unencapsulated  it  may  be  distinguished  from  simple 
thickened  pleura  by  its  change  in  level  upon  change 
in  position  of  the  patient.  Encapsulation  is  so  com- 
mon, however,  that  this  is  not  a  very  valuable  sign. 

Pulmonary  Tuberculosis. — The  present  estima- 
tion of  the  value  of  X-ray  examination  in  pulmonary 
tuberculosis  is  well-stated  in  the  following  words: 
"  although  in  the  great  bulk  of  cases,  it  (the 
stereograph)  tells  us  no  more  than  a  careful  clinical 


80  A  I^IANUAL  OF  X-RAY  TECHNIC 

examination,  yet  in  a  fair  number  of  eases,  and  these 
among  the  most  interesting  and  puzzling,  it  gives 
additional  information.  But  we  must  add  the  caution 
that  a  careful  history  is  indispensable,  since  not  even 
the  stereograph  can  tell  an  active  from  a  healed 
lesion."^ 

The  first  essential  in  studying  pulmonary  tubercu- 
losis radiographically  is  experience  in  interpreting 
the  shadows  cast  by  the  normal  chest. 

The  dense  shadow  extending  down  through  the 
middle  of  the  radiogram  is  cast  by  the  spinal  column 
and  sternum,  the  heart  and  large  blood-vessels,  the 
oesophagus,  the  trachea,  lymphatics,  and  connective 
tissue. 

On  either  side  of  the  central  shadow  is  an  irregu- 
lar shadow  of  less  density,  that  of  the  hilus.  This  is 
cast  by  the  primary  branches  of  the  pulmonary  vessels 
with  their  contained  blood,  the  walls  of  the  primary 
bronchi,  and  lymphatic  and  fibrous  tissue  surrounding 
these  structures.^ 

Radiating  from  the  hilus  are  seen  the  shadows  of 
the  heavy  trunks,  three  on  the  right  and  two  on  the 
left.  The  "  fine  linear  markings  "  are  seen  to  be 
subdivisions  of  the  heavier  trunks,  the  shadows  of 

^Wolman,  Bulletin  of  the  Johns  Hopkins  Hospital,  vol.  xxii,  No. 
245,  July,  1911. 

*  Dunham,  ibid. 


THE  THORAX  81 

which  disappear  in  normal  cases  before  the  periphery 
is  reached. 

It  has  been  definitely  proven  by  B'oardman  and 
Dunham  ^  that  the  "  linear  markings  "  in  the  radio- 
gram of  normal  lungs  are  a  composite  shadow  of  the 
artery  and  vein  and  their  contained  blood,  the 
bronchus,  and  the  supporting  connective  tissue. 

Dunham  ^  gives  the  following  as  the  changes  to  be 
found  in  early  tuberculosis: 

1.  Increase  in  area  and  density  of  the  hilus 
shadow. 

2.  Small  areas  of  great  density  in  the  hilus  due  to 
caseous,  fibrous,  or  calcified  glands. 

3.  Increase  in  density  and  breadth  of  the  heavy 
trunks  extending  towards  the  diseased  area. 

The  above  changes  may  be  due  to  mediastinitis  or 
other  conditions  and  are  not  typical  of  tuberculosis. 

4.  In  the  diseased  area  the  fine  linear  markings 
are  "  broader,  denser,  and  less  regular  in  outline,  fre- 
quently studded,  almost  to  obliteration  of  the  lines." 

The  markings  are  broken  in  continuity  and  extend 
to  the  periphery. 

Interweaving  of  the  lines  to  form  a  delicate  mesh 
is  quite  characteristic. 

As  the  lesion  progresses  the  linear  markings  be- 
come more  irregular,  the  studdings  increase  in  size 

"  Boardman  and  Dunham,  ibid. 


82  A  MANUAL  OF  X-RAY  TECHNIC 

and  density,  the  interweaving  is  closer,  and  the  entire 
diseased  area  throws  a  shadow  of  increased  density. 

Dunham  describes  tliree  branches  in  the  upper 
lobes  which  show  more  plainly  in  disease  than  in 
health  and  in  which  the  changes  described  above 
usually  make  their  first  appearance.  One  of  these, 
the  vertebral  branch,  passes  upward  from  the  hilus 
parallel  with  the  spine,  another  passes  outward  be- 
hind the  first  interspace,  and  the  third  behind  the 
second  interspace. 

Besides  these  changes  in  the  lung  markings,  cer- 
tain other  signs  of  pulmonary  tuberculosis  have  -been 
described.  One  of  these  is  limitation  in  diaphragmatic 
movement  on  the  affected  side.  When  present  this  is 
a  valuable  sign.  Other  signs  such  as  the  so-called 
"  hanging  heart,"  calcification  of  the  costal  cartilages, 
and  the  presence  of  narrow  intercostal  spaces,  are  of 
very  doubtful  value. 

It  should  be  remembered  that  pleuritic  effusion 
often  accompanies  pulmonary  tuberculosis  and  that 
it  may  be  diagnosed  radiographically  when  it  has  given 
no  clinical  signs.  There  seems  little  doubt  that  X- 
ray  examination  is  a  considerable  aid  in  the  diagnosis 
of  early  pulmonary  tuberculosis,  but  here,  as  else- 
where, it  must  be  used  in  conjunction  with  the  history 
and  all  the  other  findings. 

When  the  disease  is  advanced  and  can  be  diag- 


THE  THORAX  83 

nosed  by  clinical  signs  alone  the  X-ray  is  still  of  value 
in  determining  its  extent,  the  presence  of  small  cavi- 
ties, etc.  It  is  often  the  case  that  physical  signs  are 
present  at  only  one  apex  when  the  radiogram  shows  a 
beginning  lesion  on  the  opposite  side. 

One  of  the  principal  difficulties  is  to  distinguish 
an  old  healed  process  from  an  active  lesion.  A  point 
of  importance  in  this  connection  is  the  hazy,  blurred 
appearance  of  the  areas  of  active  disease,  in  direct 
contrast  with  the  clear-cut  outlines  of  the  healed 
lesions.  It  is  often  impossible,  however,  to  decide 
between  these  from  X-ray  examination  alone. 


CHAPTER  XI. 

X-RAY  Examination  of  the  Alimentary  Canal. 

The  alimentary  canal  can  be  studied  both  fluoro- 
scopically  and  radiographically  by  filling  the  lumen 
of  the  organs  with  some  substance  opaque  to  the  ray. 
Bismuth  in  some  form  has  been  used  more  than  any 
other  substance.  The  subnitrate  was  formerly  used, 
but  its  use  has  been  abandoned  because  of  some  cases 
of  poisoning  thought  to  be  due  to  the  formation  of 
nitrites.  Bismuth  subcarbonate  is  the  salt  now 
generally  employed.  Barium  sulphate  is  also  largely 
used  and  has  the  advantage  of  being  very  much 
cheaper  than  bismuth.  Care  must  be  taken,  however, 
to  secure  a  chemically  pure  barium  sulphate.  Such  a 
preparation  is  now  made  by  Merck  especially  for  X- 
ray  work. 

When  employing  barium  sulphate  it  is  important 
to  remember  that  it  passes  from  the  stomach  in  a 
much  shorter  time  than  bismuth  subcarbonate  and 
often  does  not  give  sufficient  time  for  a  thorough 
study  of  this  organ.  The  author's  custom  is  to  use 
bismuth  subcarbonate  for  administration  by  the  mouth 
and  barium  sulphate  for  enemata. 

The  bismuth  meal  is  prepared  by  mixing  two 
ounces  of  the  subcarbonate  with  six  ounces  of  butter- 

84 


THE  ALIMENTARY  CANAL  85 

milk,  either  natural  or  artificially  made.  Some  other 
vehicle,  such  as  cream-of- wheat  or  apple  sauce,  may  be 
used  if  the  patient  objects  to  buttermilk. 

This  meal  is  given  immediately  before  the  X-ray 
examination  is  made,  the  patient  having  been  pre- 
pared previously  by  a  light  diet  for  twenty-four  hours 
and  a  saline  laxative  the  evening  before  the  examina- 
tion. 

A  small  lead  marker  should  be  fastened  upon  the 
umbilicus,  and  no  more  than  one  thin  layer  of  cloth- 
ing, without  buttons  or  metallic  fasteners,  should  be 
between  the  patient  and  the  plate. 

The  (Esophagus. — Examination  of  the  oesoph- 
agus is  made  both  fluoroscopically  and  radiographi- 
cally.  Fluoroscopic  examination  is  carried  out  by 
having  the  patient  stand  with  his  chest  against  the 
screen,  the  ray  passing  from  behind.  He  is  then 
Totated  slightly  toward  his  right  so  that  the  ray 
enters  just  outside  of  the  angle  of  the  left  scapula  and 
passes  obliquely  through  the  chest.  This  is  the  best 
position  both  for  fluoroscopy  and  radiography  of  the 
structures  of  the  posterior  mediastinum. 

To  examine  the  oesophagus  it  is  necessary  for  the 
patient  to  swallow  a  bismuth  mixture.  The  passage 
of  the  bismuth  to  the  stomach  is  followed  on  the 
screen  and  stoppage  or  deflection  of  the  shadow  noted. 
Normally  the  bismuth  passes  steadily  down  the  oesoph- 


86  A  MANUAL  OF  X-RAY  TECHNIC 

agus  with  sometimes  a  slight  pause  and  backward 
deflection  as  it  passes  behind  the  arch  of  the  aorta, 
with  a  little  longer  delay  at  the  cardiac  end. 

Obstruction  to  the  oesophagus  may  be  caused  by 
(1)  pressure  from  without;  (2)  spasmodic  or  reflex 
contraction;  (3)  organic  disease  of  the  walls;  (4) 
presence  of  a  foreign  body. 

In  order  to  differentiate  the  above  conditions, 
great  care  must  be  exercised  in  studying  the  screen 
picture  and  in  interpreting  radiograms.  Pressure 
from  without  may  be  due  to  aortic  aneurism,  medias- 
tinal tumor,  enlarged  glands,  or  disease  of  the  spine. 
Aortic  aneurism  and  spinal  disease  can  usually  be 
diagnosed  by  X-ray  examination,  but  the  others  are 
more  difficult. 

Obstruction  from  whatever  cause  unless  relieved 
finally  produces  dilatation.  Even  cases  of  reflex  con- 
tractions and  cardiospasm  in  which  no  cause  can  be 
discovered  often  produce  extreme  dilatation  (Fig. 
24). 

X-ray  study  of  the  oesophagus  is  very  valuable  to 
locate  the  site  of  an  obstruction  or  dilatation  and 
sometimes  gives  very  definite  information  as  to  the 
cause.  In  this  as  in  other  parts  of  the  body,  however, 
the  X-ray  examination  must  be  taken  in  conjunction 
with  all  the  other  findings,  and  great  care  must  be 
exercised  in  interpreting  the  X-ray  evidence. 


Fig.  24. — Constriction  at  cardiac  end  of  stomach.     Note  large  amount  of  bismuth  in 
lower  end  of  oesophagus  and  the  long  stomach  extending  down  into  the  pelvis. 


THE  ALIMENTARY  CANAL  87 

The  Stomach. — To  study  this  organ  by  means  of 
the  X-ray  several  different  methods  and  combinations 
of  methods  are  advocated.  Some  radiologists  use 
only  the  fluoroscope,  to  the  complete  exclusion  of 
radiography.  This  is  more  common  in  Europe  than 
in  America.  Others  use  only  the  radiographic  method 
with  patient  erect  or  prone,  while  still  others  employ 
both  fluoroscopy  and  radiography.  The  author's 
routine  is  to  give  the  bismuth  meal,  and  then  with 
the  patient  in  the  prone  position  to  take  several  radio- 
grams, varying  from  six  to  ten,  at  intervals  of  three 
to  five  minutes,  depending  upon  the  rapidity  with 
which  the  stomach  empties  itself.  One  or  two  radio- 
grams are  then  taken  in  the  upright  position,  and 
finally  the  action  of  the  stomach  is  observed  on  the 
screen.  Another  radiogram  is  made  after  an  interval 
of  six  hours  to  determine  the  time  it  takes  for  the 
stomach  to  completely  empty  itself. 

The  appearance  of  the  normal  stomach  varies  con- 
siderably in  difl'erent  individuals  and  in  the  same  in- 
dividual as  a  result  of  different  postures,  pressure,  etc. 

The  most  important  region  for  study  is  that  of 
the  pylorus,  including  the  terminal  portion  of  the 
stomach,  the  region  of  the  sphincter,  and  the  first 
part  of  the  duodenum.  This  latter  plays  a  very  im- 
portant part  in  X-ray  diagnosis  of  stomach,  duo- 
denal, and  gall-bladder  conditions.  Because  of  the 
way  it  is  placed  with  relation  to  the  pylorus  it  is 


88  A  MANUAL  OF  X-RAY  TECHNIC 

called  the  "  cap."  Figs.  25,  26,  27,  and  28  illustrate 
the  diiFerent  appearances  of  normal  stomachs  and 
duodenal  caps. 

The  gastric  and  duodenal  surfaces  of  the  normal 
cap  should  be  smooth  and  regular,  and  the  lumen 
centrally  located.  Deformity  or  malposition  of  the 
cap  is  one  of  the  most  constant  of  the  radiologic  evi- 
dences of  adhesions,  which  may  be  due  to  gastric  or 
duodenal  ulcers  or  to  gall-bladder  disease. 

The  following  radiologic  indications  of  adhesions 
are  given  by  Cole:^ 

1.  The  lumen  varies  in  diameter,  but  does  not 
dilate  to  the  normal  size. 

2.  The  rugae  show  unusually  distinctly,  have  a 
crinkled  appearance,  and  run  obliquely  or  trans- 
versely. 

3.  The  peristaltic  contractions  are  clear-cut  in  the 
normal  portion,  but  cease  or  are  distorted  when  they 
reach  the  adhesions. 

4.  The  cap  is  constricted,  asymmetrical,  dis- 
placed, or  absent. 

5.  The  duodenum  is  angular  or  contracted. 
Figs.  29,  30,  and  31  illustrate  cases  with  adhesions 

due  to  various  causes. 

Gall-stones,  unfortunately,  only  rarely  cast 
shadows,  but  adhesions  due  to  gall-bladder  disease 
can  often  be  diagnosed.    In  these  cases  the  malforma- 


»Cole,  Archives  of  the  Rontgen  Ray,  October,  1912. 


Fig.  31. — Adhesions  causing  distortion  of  cap,  result  of  old  ulcer. 


Fig.  32. — Carcinoma  of  stomach. 


THE  ALIMENTARY  CANAL  89 

tion  of  the  cap  may  be  only  on  the  right  side,  and  the 
cap  itself,  instead  of  being  placed  centrally  upon  the 
pylorus,  is  likely  to  be  angulated.  The  entire  pyloric 
region  of  the  stomach  may  be  more  or  less  fixed  at  a 
point  considerably  farther  to  the  right  than  usual. 

Carcinoma  of  the  stomach  (Fig.  32)  gives  a 
very  characteristic  picture  in  advanced  cases,  and  even 
in  early  cases  it  is  quite  often  possible  to  make  a 
diagnosis  of  the  presence  of  adhesions  with  very  prob- 
able beginning  carcinoma.  The  diagnosis  is  based 
upon  irregularity  in  the  outline  of  the  stomach  ap- 
pearing constantly  on  the  screen  and  on  successive 
plates.  "  The  lumen  of  the  stomach  is  encroached 
upon  by  a  nodular  growth  in  the  wall  of  the  viscus, 
with  islands  or  projections  into  the  normal  tissue, 
giving  the  appearance  of  finger-prints.  The  line  of 
invasion  may  have  a  worm-eaten  appearance  with 
overhanging  edges,  or  the  growth  may  progress  in 
the  form  of  a  cone,  terminating  at  its  apex  in  a  small 
constricted  lumen,  which  may  be  reduced  to  one- 
eighth  inch  in  diameter,  and  filled  with  bismuth  or 
entirely  obliterated."^ 

Functional  and  organic  hour-glass  contractions  of 
the  stomach  are  often  difficult  to  differentiate.  The 
spasmodic  constriction  which  most  often  occurs  about 
the  junction  of  the  upper  and  middle  thirds  of  the 
stomach  may  be  purely  functional,  or  may  be  due  to 
a  reflex  contraction  caused  by  ulcer,  or  it  may  be  a 


90 


A  MANUAL  OF  X-RAY  TECHNIC 


true  organic  condition.  Ulcer  may  be  quite  certainly 
diagnosed  at  the  site  of  a  spasmodic  constriction  if 
clinical  signs  and  sj^mptoms  are  present,  but  not 
otherwise.  To  differentiate  the  spasmodic  from  the 
real  organic  hour-glass  stomach  it  is  necessary  to 
observe  the  screen  shadow  for  some  time  or  to  take 
a  series  of  pictures  at  rather  long  intervals.  If  the 
contraction  is  only  spasmodic,  relaxation  may  occur 
after  a  time,  especially  if  massage  is  practised,  while 
the  organic  contraction  remains  constant. 

Cole  gives  the  following  distinguishing  points 
between  carcinoma,  hour-glass  constriction,  and  ad- 
hesions^ : 


Carcinoma.. 

1.  The  lumen  of   the 

constricted  area 
is  constant  in  size, 
shape,  and  posi- 
tion. 

2.  The  growth  is  rela- 

tively wide. 


3.  The  rugse  are   ab- 
sent. 


4.  The  peristaltic  con- 
tractions are  ab- 
sent. 


The  line  of  invasion 
is  characterized 
by  nodular  in- 
dentations simi- 
lar  1 0  finger- 
prints. 


HouE- Glass    Constric- 
tion. 

1.  The  lumen  of  the 

constricted  area 
is  constant  in  size 
and  shape,  but 
not  necessarily  in 
position. 

2.  The   area    or    con- 

striction is  rela- 
tively narrow,  or 
ring-like. 

3.  Peristalsis  is  present 

in  either  or  both 
segments  and  the 
ring  very  closely 
resembles  a  peris- 
taltic contraction. 

4.  The  line  of  involve- 

ment is  smooth, 
and  shows  no  evi- 
dence of  nodular 
indentations. 


Adbesions. 

1.  The   lumen    varies 

in  diameter,  but 
never  completely 
expands  or  con- 
tracts. 

2.  The  area  or  involve- 

ment may  be  ex- 
tensive or  local- 
ized. 

3.  The  rugse  show  un- 

usually distinctly, 
generally  running 
transversely  or 
obUquely. 

4.  The  peristaltic  con- 

tractions in  the 
involved  area  are 
wider  than  nor- 
mal. 

5.  The  line  of  invasion 

may  be  sharp  or 
serrated,  and 
shows  no  nodular 
indentations. 


Fig.  33. — Obstruction  at  pyloric  end  of  .stomach,  probably  carcinoma. 


Fig.  34. — Angulation  of  cap  and  "under-shot"  appearance  of  stomach. 


THE  ALIMENTARY  CANAL  91 

Pyloric  obstruction  (Fig.  33)  may  be  diagnosed 
radiologically  by  the  occurrence  of  exaggerated  peri- 
staltic action,  the  retention  of  bismuth  for  longer  than 
six  hours  when  the  peristaltic  action  is  good,  and  by  a 
characteristic  "  under-shot  "  or  prognathous  appear- 
ance of  the  stomach  (Fig.  34). 

In  judging  the  length  of  time  that  it  takes  for  the 
stomach  to  empty  itself  care  must  be  taken  that  no 
food  is  introduced  into  the  stomach  between  the  time 
of  the  bismuth  meal  and  the  taking  of  the  second 
radiograms  some  hours  afterward.  If  food  is  taken 
it  mixes  with  the  bismuth  still  present  and  causes  its 
retention  much  longer  than  would  be  the  case  other- 
wise. 

Other  facts  that  may  be  determined  readily  with 
regard  to  the  stomach  are  its  size  (Figs.  35  and  36) 
and  its  position  (Fig.  37). 

The  duodenum  is  not  so  readily  studied  radio- 
logically  as  the  stomach,  because  of  the  rapidity  with 
which  the  food  passes  through  it.  It  has  been  ob- 
served by  many  radiologists,  however,  that  unusually 
rapid  emptying  of  the  stomach  takes  place  in  the 
presence  of  duodenal  ulcer.  This  accords  with  the 
author's  experience  and  it  may  be  said  with  confidence 
that  this  is  a  valuable  confirmatory  sign  of  ulcer  of 
the  duodenum.  In  these  cases  the  stomach  may  com- 
pletely empty  itself  in  from  one-half  hour  to  an  hour. 


92  A  MANUAL  OF  X-RAY  TECHNIC 

Obstruction  in  the  duodenum  may  be  due  to 
spasm  caused  by  ulcer,  or  to  adhesions.  It  may  be 
shown  in  the  radiogram  by  an  enlargement  of  the 
bismuth  shadow  (Fig.  38). 

The  normal  jejunum  and  ileum  do  not  yield 
much  information  from  X-ray  study  because  of  the 
rapidity  of  the  j)assage  of  the  food  and  the  super- 
imposing of  the  shadows  of  the  various  coils. 

Obstruction  at  any  point  is  shown  by  an  accumula- 
tion of  the  bismuth. 

Kinks  and  constrictiions  in  the  terminal  ileum 
often  show  quite  plainly  in  radiograms. 

The  Colon. — The  large  intestine  may  be  studied 
after  the  administration  of  a  bismuth  meal  or  by  giv- 
ing an  enema. 

The  author's  practice  in  preparing  the  enema  is  to 
mix  six  ounces  of  barium  sulphate  with  one  and  one- 
half  to  two  liters  of  warm  water,  to  which  is  added 
one  ounce  of  powdered  gum  arable  to  assist  in  keep- 
ing the  barium  sulphate  in  suspension.  The  patient 
is  placed  on  his  side  with  the  hips  slightly  elevated 
and  the  suspension  allowed  to  flow  into  the  bowel 
very  slowly  through  a  tube  introduced  to  a  distance 
of  six  or  eight  inches.  When  the  entire  amount  has 
entered  the  patient  assumes  the  knee-chest  posture 
for  about  three  minutes  and  then  lies  upon  the  right 
side  for  about  the  same  length  of  time. 


Fig.  37. — Ptosis  of  stomach,  patient  erect. 


Fig.  .38. — Obstruction  in  second  part  of  duodenum. 


Fig.  39. — Colon  ami  sigiuuid  with   patient  prone. 


Fig.  40. — Same  case  with  patient  erect.  Note 
redundancy  of  .sigmoid  with  patient  prone  and  the 
pressure  of  the  transverse  colon  upon  the  sigmoid  with 
patient  erect. 


Fig.  41. — Dilated  cseeum. 


Fig.  42. 


-Same  case  after  operation  (plication), 
ing_much  smaller  cseeum. 


^how- 


THE  ALIMENTARY  CANAL  93 

The  above  procedure  secures  the  complete  filling 
of  the  colon,  including  the  caecum,  in  practically  every 
case. 

The  average  time  for  the  bismuth  to  reach  the 
cgecum  after  the  meal  is  about  four  and  one-half  hours, 
and  it  is  usually  through  the  sigmoid  within  twelve 
hours. 

If  kinks  or  constrictions  are  discovered  it  is  well 
to  confirm  their  presence  by  an  examination  made 
after  an  enema. 

Stereoradiograms  are  often  of  great  aid  in  de- 
ciding upon  the  true  position  of  different  parts  of  the 
large  intestine,  especially  the  relation  of  coils  of  the 
colon  to  the  sigmoid. 

The  position  of  the  colon  with  the  patient  prone 
often  corresponds  to  the  text-book  pictures,  but  varies 
greatly  with  the  patient  erect. 

Ptosis  of  the  Colon  (Figs.  39  and  40). — Even 
in  normal  cases  the  transverse  colon  makes  a  consider- 
able downward  curve  when  the  patient  is  erect,  but  in 
cases  of  ptosis  both  the  hepatic  and  splenic  flexures 
may  descend  and  the  transverse  colon  may  be  well 
down  in  the  pelvis. 

The  colon  is  a  very  movable  viscus  and  it  is  often 
of  great  importance  to  determine  whether  some  seem- 
ingly abnormal  position  is  a  fixed  one.  This  may  be 
done  by  taking  pictures  both  in  the  horizontal  and 


94  A  MANUAL  OF  X-RAY  TECHNIC 

erect  positions  after  the  bismuth  meal,  and  confirming 
these  findings  by  examination  after  an  enema. 

The  cause  of  constipation  maj^  be  found  in  a  kink 
or  constriction  at  any  point  in  the  colon;  in  a  large, 
dilated  caecum;  in  a  long,  redundant  sigmoid;  or  in 
ptosis  of  the  transverse  colon  pressing  upon  the 
sigmoid  (Figs.  39  and  40). 

Sometimes  it  is  found  after  an  enema  that  the 
bismuth  passes  back  through  the  ileocecal  valve  and 
fills  from  a  few  inches  to  several  feet  of  the  ileum. 
The  exact  importance  of  this  is  not  yet  fully  under- 
stood. 

The  vermiform  appendix  sometimes  fills  with  the 
bismuth  and  shows  plainly  in  the  radiogram.  No 
importance  is  attached  to  this  by  the  majority  of 
observers. 


CHAPTER  XII. 

The  Urinary  System. 

Fluoroscopy  is  of  very  little  value  in  examination 
of  the  urinary  system.  Radiograms  furnish  the  only 
reliable  evidence  upon  which  to  base  either  positive 
or  negative  diagnoses. 

Technic  of  Examination. — The  most  pains- 
taking care  in  technic  is  necessary  in  radiography  of 
the  kidneys,  ureters,  and  bladder. 

The  first  essential  is  the  thorough  preparation  of 
the  patient,  without  which  X-ray  examination  is 
valueless.  A  very  light  diet  should  be  taken  for 
twenty-four  hours  previous  to  the  examination,  and 
the  bowels  should  be  thoroughly  cleared  by  means  of 
aperients.  An  enema  should  be  given  shortly  before 
the  examination  is  made.  Fecal  shadows  make  it  very 
difficult  to  arrive  at  correct  conclusions,  and  for  this 
reason  it  is  often  necessary  for  the  patient  to  continue 
on  a  restricted  diet  for  an  additional  twenty-four 
hours  and  to  undergo  a  second  preparation  by  means 
of  purgatives  and  enemata.  The  best  of  technic  will 
fail  to  produce  satisfactory  results  if  the  patient  is 
not  thoroughly  prepared. 

The  examination  should  include  a  radiogram  of 
each  kidney  region,  one  covering  the  course  of  each 

95 


96  A  MANUAL  OF  X-RAY  TECHNIC 

ureter,  and  one  of  the  pelvis,  five  in  all.  This  is 
always  necessary  because  it  has  often  happened  that 
the  radiogram  showed  the  stone  in  the  opposite  kidney 
from  the  one  suspected,  while  in  other  cases  there 
may  be  calculi  on  both  sides.  The  pelvis  must  be 
included  because  the  stone  which  has  caused  the  renal 
symptoms  may  have  passed  into  the  bladder. 

Plates  8  X  10  inches  in  size  have  been  found  the 
most  satisfactory  because  their  area  can  be  completely 
covered  by  the  ray  with  the  use  of  a  rather  small 
cylindrical  diaphragm. 

A  soft  tube  with  sharp  focus  and  having  clear- 
cut  hemispheres  should  be  used.  A  tube  which  is  too 
hard  fails  to  give  the  detail  in  the  soft  structures 
essential  to  a  good  radiogram  of  the  kidney  regions, 
and  may  fail  to  show  the  softer  calculi. 

Compression  by  means  of  some  form  of  compres- 
sion diaphragm,  rubber  bag,  or  other  apparatus  is  a 
valuable  aid  in  securing  good  detail,  because  it  dis- 
places the  abdominal  contents  over  the  kidney. 

The  plate  for  the  kidney  should  be  so  placed  that 
the  last  two  ribs  and  the  first  three  lumbar  vertebras 
will  show  upon  it.  The  target  is  adjusted  over  the 
centre  of  the  plate  at  a  distance  of  about  eighteen 
inches,  and  the  exposure  made  while  the  patient  holds 
the  breath. 


THE  URINARY  SYSTEM  97 

The  essential  features  of  a  satisfactory  radiogram 
of  the  kidney  region  are  that  it  shall  show  clearly  the 
last  two  ribs,  the  three  upper  lumbar  vertebrae  includ- 
ing the  transverse  processes,  the  outline  of  the  psoas 
muscle,  and  the  crest  of  the  ilium.  It  is  now  often 
possible  to  show  the  outline  of  the  kidney  itself.  It  is 
important  to  use  every  effort  to  do  this,  for  if  a  radio- 
gram gives  sufficient  detail  to  show  the  kidney  a 
negative  diagnosis  of  calculus  can  be  based  upon  it 
with  only  very  slight  probability  of  error.  Even  in 
very  fat  patients  with  thorough  preparation  and  the 
use  of  good  compression  the  kidney  shadow  may  be 
shown. 

The  plate  for  the  ureter  should  show  the  third, 
fourth,  and  fifth  lumbar  vertebrae  and  the  sacro-iliac 
synchondrosis,  while  that  of  the  pelvis  should  include 
both  sacro-iliac  synchondroses,  the  sacrum,  and  the 
coccyx  to  its  tip. 

Calculus. — The  greatest  value  of  radiography  of 
the  urinary  tract  has  been  in  the  diagnosis  of  calculus. 
Formerly  it  was  thought  that  only  a  positive  finding 
was  of  value,  but  with  improved  technic  such  fine 
detail  can  now  be  obtained  that  the  errors  in  negative 
diagnosis  are  very  few. 

The  positive  diagnosis  of  renal  calculus  is  based 
upon  the  presence  of  a  definite  shadow  over  the  kidney 


98  A  jSIANUAL  OF  X-RAY  TECHNIC 

region.  If  the  shadow  of  the  kidney  itself  shows  on 
the  plate  no  difficulty  is  experienced  in  locating  the 
stone  either  in  the  pelvis  or  cortex  of  the  kidney.  The 
shadow  is  sometimes  between  the  eleventh  and  twelfth 
ribs  but  more  often  below  the  twelfth  rib.  If  the 
kidney  is  in  its  normal  position  the  shadow  is  always 
internal  to  a  line  erected  perpendicularly  from  the 
middle  of  the  iliac  crest. 

A  stone  in  the  ureter  produces  a  shadow  some- 
where along  the  line  of  the  tips  of  the  transverse  proc- 
esses of  the  lumbar  vertebrae  or  over  the  sacro-iliac 
synchondrosis.  In  the  great  majority  of  cases  it  lies 
below  the  pelvic  brim. 

Differential  Diagnosis. — Calcareous  glands  re- 
semble calculi  but  may  be  distinguished  from  them 
by  their  more  irregular  outline  and  the  fact  that  they 
are  not  usually  over  the  course  of  the  ureter. 

Small  calcareous  bodies  called  phleboliths  some- 
times appear  along  the  lower  part  of  the  ureter,  but 
they  are  usually  multiple,  and  may  be  arranged  in  a 
line  at  an  angle  to  the  course  of  the  ureter. 

Fecal  concretions  or  foreign  bodies  in  the  intestine 
are  distinguished  from  calculi  by  the  fact  that  they 
change  position  or  disappear  entirely  if  several  ex- 
aminations are  made. 

Gall-stones    only    rarely    throw    dense    enough 


THE  URINARY  SYSTEM  99 

shadows  to  be  seen  on  the  radiogram  and  when  they 
do  they  usually  have  a  fairly  characteristic  appear- 
ance. Because  of  the  greater  density  of  the  outer 
layer  of  the  stone  the  shadow  has  a  ring-shaped  ap- 
pearance with  a  dark  centre.  Gall-stones  may  also 
be  distinguished  from  renal  calculi  by  the  fact  that 
they  show  much  better  when  the  patient  lies  with  the 
abdomen  next  to  the  plate,  while  renal  calculi  cast 
their  sharpest  shadow  with  the  patient  on  the  back. 

Difficulty  in  the  diagnosis  of  renal  calculus  may 
arise  because  of  displacement  of  the  kidney  from  its 
normal  position.  The  kidney  may  then  be  located  by 
the  injection  into  the  pelvis  through  a  ureteral 
catheter  of  some  form  of  silver  preparation  such  as 
collargol. 

Sometimes  a  calcareous  gland  or  other  calcified 
body  may  throw  a  shadow  directly  on  the  line  of  the 
ureter.  It  then  becomes  necessary  to  take  other  radio- 
grams with  a  bismuth-impregnated  ureteral  catheter 
in  position.  It  must  not  be  inferred,  however,  that  a 
shadow  is  not  that  of  a  ureteral  calculus  simply  be- 
cause the  catheter  can  be  passed  beyond  it,  for  this 
has  frequently  happened.  Radiograms  at  different 
angles  and  also  stereoradiograms  will  need  to  be  taken 
to  establish  the  exact  relation  of  the  shadows. 

The  pelvis  may  be  radiographed  with  the  patient 


100  A  MANUAL  OF  X-RAY  TECHNIC 

lying  upon  his  back  or  upon  his  abdomen.  If  the 
latter  position  is  used  it  is  well  to  tilt  the  tube  so  that 
tlie  rays  pass  obliquely  forward  and  toward  the 
patient's  head.  This  prevents  superimposing  the 
shadow  of  the  sacrum  upon  the  region  of  the  bladder. 
Radiography  is  of  great  value  in  cases  of  vesical 
calculus,  since  it  not  only  reveals  the  stones  which 
might  be  discovered  by  the  sound,  but  also  shows  the 
presence  of  stones  which  are  encysted  and  cannot  be 
discovered  by  the  sound. 


INDEX 


Abscess,  alveolar,  75 

Accelerator,  sodium  carbonate  as, 

48 
Alimentary      canal,      radiography 

of,  84 
Amidol,  48 

Ampere,  definition  of,  3 
Aneurism,   thoracic,   78 
diagnosis  of,  78 
fluoroscopy  in^  78 
Ankle,  radiography  of,  67 
Anode,  accessory,  14,  16 
Anti-cathode,  14 
Appendix,  vermiform,  94 
Arrhenius,  theory  of,  2 
Arthritis   deformans,   69 
Barium  sulphate,  84 
Batteries,  electric,  32 

galvanic,  2 

storage,  32 
Benoist,   radiochromomet'er  of,  22 
Bismuth  enema,  92 

meal,  84 

subcarbonate,   84 

subnitrate,    84 
Bones,  cysts  of,  71 

diseases  and  injuries  of,  65,  67 

exostoses  of,  70 

sarcoma  of,  68 

syphilis  of,   68 

tubercular   disease   of,   68 
Cathode,  aluminum,  14 
Cathode  rays,  11 
Cell,  galvanic,  2,  6 
Daniell,  3 

potassium  bichromate,  3 
Coil,  induction,  26 


Colon,  92 

constriction  of,  93 

enema  for  examination  of,  92 

ptosis  of,  93 
Conduction,  6 
Constipation,  causes  of,  94 
Copper    wire     best     for    conduc- 
tors, 45 
Coulomb,  definition  of,  4 
Current  for  induction  coil,  33 

for  transformer,  38 
Current  strength,  unit  of,  4 
Developing  solutions,  49 
Diaphragm,    diminished    excursion 

of,  77 
Duodenum,    obstruction   of,    92 
Eikonogen,  48 
Elbow,    radiography   of,    67 
Electricity,  1 

dynamic,   1 

faradic,  1 

galvanic,   1 

nature  and  properties  of,  1 

static,  1 
Electrification,  kinds  of,  6 
Electro-magnet,  8,  9 
Electro-motive  force,  unit  of,  4 
Elektron,    I 

Enchondroma,     differential     diag- 
nosis of,  70 
Exostoses,  70 
Exposure,  length  of,  52 
Fixing  solutions,  53 
Fluoroscopy,  dangers  of,  31,  56,  58 

description  of,  57 

examination  of  chest  by,  58 

examination  of  colon  by,  58 

examination  of  stomach  by,  58 
101 


102 


INDEX 


Foreign  bodies,  61,  75 
in  the  eye,  64 
localization  of,  61 

Mackenzie-D  a  v  i  d  s  o  n 

method,  62 
stereoscopic,   61 
triangulat^on    method,    62 
Gall-stones,  89,  98 
Grouping  of  galvanic  cells,  5 
Head,  fractures  of,  72 

new  growths  of,  72 
Heart,  radiography  of,  78 
Hip,  radiography  of,  67 
Hydroquinon,  49 
Induction,   6 
coil,  25 

alternating    current    with, 
27 
Intensification,  55 
Interrupter,  28 
electrolytic,  30 

Caldwell-Simon,   32 
Wehnelt,  31 
mechanical,  28 
mercury,   29 
dipper,  29 
jet,  30 
rotary,   30 
vibrating,   28 
Iridium  target,  16 
Inverse  currents,  26 
Kidney,  calculus  of,  96 
diagnosis   of,  96 
technic  of  examination  of,  96 
Knee,  radiography  of,  67 
Light,      action     on     photographic 

plates,  47 
Localization     of     foreign     bodies, 

61,  64 
Lungs,  normal,  76 

hilus  of,  80 
Magnet,  7 


Magnetic  field,  7 

Mediastinum,     posterior,      tumors 

of,  78 
Mercuric   chloride    for  intensifica- 
tion, 55 
Metol,  48,  60 
Milliammeter,  21 
CEsophagus,  dilatation  of,  86 

fluoroscopy  of,  86 

obstruction  of,  86 

radiography  of,  85 
Ohm,  definition  of,  3 
Ohm's  law,  4,  45 
Ortal,   48 
Oscilloscope,  26 

Osmium  as  material  for  target,  16 
Osteomyelitis,  67,  68 
Osteosarcoma,  68,  70 

differential  diagnosis  of,  from 
syphilis,  68 
Parallel,  grouping  of  cells  in,  5 
Periostitis,  67 
Platefi,   photographic,   47 

intensification      of      under-ex- 
posed, 55 

reduction  of  over-exposed,  64 

silver  salts  on,  48 

X-ray,  51 
Platinum   as   material   for   target, 

15 
Pleurisy,   acute,  with  effusion,   79 
Pneumothorax,  76 
Polarization  action  in  rectifier,  33 
Potassium  bromide  as  restrainer,  49 

cyanide  as  reducer,  64 

permanganate,  54 
Preservative,    sodium    sulphite    as, 

49 
Pulmonary  tuberculosis,  79-83 
Pylorus,  obstruction  of,  91 

adhesions  of,  88 
Pyorrhoea  alveolaris,  75 


INDEX 


103 


Pyrogallic  acid  as  reducer,  48 
Radiochromometer   of   Benoist,  22 
Radiography,  47,  51 
dental,  74 
stereoscopic,  59 

advantages  of,  60 

apparatus  for,  60 

for  dislocations,  60 

for  fractures,  60 

for  localization  of  foreign 

bodies,   61 
technic  of,  60 
Rays,  20 

cathode,   11 

properties  of,  11 
relation  to  X-rays,  12 
indirect,   20 
inverse,    26 
secondary,  20 
Rectifier,  33 

aluminum  cell,  33 
mercury  arc,  35 
mercury  vapor,  35 
Reducer,  function  of,  64 
Resistance,  electrical,  3,  4 
Restrainer,  potassium  bromide  as, 

48,  49 
Rheostat,  46 
Rodinal,  48 
Screen,  fluoroscopic,  77 

intensifying,  52 
Series,  grouping  cells  in,  5 
Shoulder,  radiography  of,  66 
Sinuses,   accessory,   72 
frontal,  73 
maxillary,  73 
sphenoidal,   73 
Solenoid,  9 
Spark-gap,  21 

adjustable,  27 
Spinal  column,  66 
Spondylitis  deformans,  70 


Static   electricity,   1 
machine,   26 
Stomach,    appearance    of    normal, 
87 

carcinoma  of,  89 
fluoroscopy  of,  87 
hour-glass  contractions  of,  89 
pyloric  region  of,  87,  91 
ulcer  of,  88 
Target  of  X-ray  tube,  15 
Teeth,  radiography  of,  76 
Terminals,   positive    and    negative, 

means  of  determining,  23 
Thorax,  fluoroscopy  of,  76 
radiography   of,    76 
stereoscopic,   76 
Transformer,  36 

advantages  of,  38 
alternating  current  for,  38 
description  of,  36 
direct  current  for,  38 
oil  as  insulation,  38 
ring  type  of,  37 
shell  or  jacket  type  of,  38 
"  step-up  "    and    "  step-down," 
37 
Tubes,  vacuum,   13 
care  of,  22 
Crookes,  13 
directions    for   regulating, 

19 
for  induction  coil,  26 
Geissler,  10 

modern  type  of  X-ray,  15 
Queen's       self-regulating, 

17 
valve  or  ventril,  27 
Villard,  27 
water-cooled,  16 
Ulcer  of  duodenum,  88,  91 
of  stomach,  88 


104 


INDEX 


Ureter,  calculus  of,  97,  99 
radiography  of,  98 
Urinary  system,  95 

fluoroscopy  of,  95 
radiography  of,  95 
Vacuum,    10 

devices  for  regulating,  16-18 
directions   for  regulating,  19 
Valve,  ileocaecal,  94 

tube,  27 
Volt,  definition  of,  4 


Watt,  definition  of,  4 
X-ray,  10 

discovery  of,  11 

history  of,  10-12 

penetrative  power  of,  21 

plates,  48 

properties  of,  12 

relation  of,  to  cathode  ray,  13 

source   of,    12 

tubes,  10,  1^16,  21,  22 


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THE  UBRARY 

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A  manual  of 

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1913 

x-ray  technic . 

Biomedical 
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Biomedicat 
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160 

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